The Flatiron and its siblings: 10 stunning triangular-shaped buildings you need to know about

A collection of buildings that exploit the planivolumetric constraints of triangular lots through their iconic flatiron shape, becoming urban landmarks from New York to Turin to Japan.

Alessandro Antonelli, Scaccabarozzi House, Turin, Italy 1840 This singular building located in a triangular plot of narrow dimensions, nicknamed "fetta di polenta" (slice of polenta), is the result of the challenge Antonelli undertook to create a dwelling that would fill the limited floor space in height. The construction, raised in 1881, is therefore a sleek volume on a narrow base, characterised inside by rooms conformed to this shape with triangular rooms and custom-made furniture.

Photo Katell Ar Gow from Flickr

Alessandro Antonelli, Scaccabarozzi House, Turin, Italy 1840

Photo Katell Ar Gow from Flickr

David Robert jr, Gooderham Building, Toronto, Canada 1892 Gooderham Building, nestled in a triangular lot between Front Street and Wellington Street in downtown Toronto, is one of the earliest examples of “flatiron” buildings in the city and the country. The massive volume of red brick and copper roofing with dormer windows and gables features eclectic suggestions. 

Photo Bernard Spragg.NZ on Flickr

David Robert jr, Gooderham Building, Toronto, Canada 1892

Photo Will Buckner on Flickr

Daniel Burnham, Flatiron Building, New York, USA 1902 Considered one of Manhattan’s best known landmarks, the Fuller Building (better known as the Flatiron Building) with its pronounced triangular shape, its 87 m height and 22 floors of office space fills the area at the intersection of Fifth Avenue and Broadway. The building is characterised by limestone and terracotta façades mounted on structural steel frames, in accordance with the type of construction common at the time of the first skyscrapers.

Photo Alberto Giron on Adobe Stock

Daniel Burnham, Flatiron Building, New York, USA 1902

Photo travelview on Adobe Stock

Jules and Raymond Février, Esteve Fernández-Caballero, Metrópolis, Madrid, Spain 1911 The five-storey building between Gran Via and Calle Alcalà in the centre of Madrid, originally designed to house the offices of an insurance group, is characterised by a Beaux-Arts style with fronts supported by imposing Corinthian columns and allegorical sculptures, and surmounted by a slate dome with gold leaf trim and a winged victory. 

Photo Luis García su wikimedia commons

Jules and Raymond Février, Esteve Fernández-Caballero, Metrópolis, Madrid, Spain 1911

Photo Diego Delso on wikimedia commons

László Hudec, Wukang Mansion, Shanghai 1924 The Wukang Mansion is a residential complex that originally housed 63 flats and 30 servants' quarters, designed by Hungarian-Slovak architect László Hudec, a famous name in Shanghai. The unusual wedge shape – due to the conformation of the lot located at the southern end of Wukang Road, at the corner with Middle Huaihai Road – and the 30 m high concrete and masonry volume make it a clearly recognisable element in the context. It has been home to several celebrities over time and still retains its residential function today. 

Foto 钉钉 on wikimedia commons 

László Hudec, Wukang Mansion, Shanghai 1924

Photo guineapig33 on Flickr

Durbach Block Jaggers Architects, 5 – 9 Roslyn St, Sydney, Australia 2009 The triangular shape and small size of the site dictated the plan-volume layout of this four-storey commercial building in Kings Cross, which houses a restaurant on the ground floor and a green roof terrace. The design choices intentionally detach the intervention from the current typology of masonry buildings typical of the area, favouring a plastic volume with a vaguely expressionist flavour, covered with variegated tiles, glossy and matt, white and beige, on which the surrounding environment is reflected.

Photo Julia Charles

Durbach Block Jaggers Architects, 5 – 9 Roslyn St, Sydney, Australia 2009

Foto Julia Charles

Sebastian Nagy | architects, Triangolo, Spojovacia, Nitra, Slovakia 2009 The triangular apartment building combines the rigorous and essential character of the elevation, with its monomaterial fronts, with the sinuous and lively course of the roof that celebrates the surrounding landscape of Zobor, of the Nitra Plateau and the homonymous river.

Photo Bobo Boška

Sebastian Nagy | architects, Triangolo, Spojovacia, Nitra, Slovakia 2009

Photo Bobo Boška

Eastern Design Office, On the Corner, Shiga, Japan 2011 Situated in the Youkaichi district, in a mixed-use area – industrial and residential – frequented by immigrants and commuters, the building with seven rental flats is located in a plot long abandoned due to its pronounced triangular shape, considered unattractive to the market. The intervention brings the peculiar urban space back to life, redeeming it through an architectural operation with a strong visual and vaguely surreal impact, amidst intentionally accentuated sharp edges, material textures of stone, cement and glass and lively chiaroscuro effects.

Photo Koichi Torimura

Eastern Design Office, On the Corner, Shiga, Japan 2011

Photo Koichi Torimura

LAN Architecture, 40 Housing Units, Paris, France 2014 The intervention located in the new Clichy-Batignolles mixed development area is a homage to 19th century Paris, to the urban transformation planned by Haussmann in particular, with the new major circulation axes generating new forms and typologies for blocks and buildings at their intersections. The volume fits into a triangular plot, whose geometry it recovers and exploits the spatial potential. The spaces allow for complete reversibility from residential to tertiary use. The façades are characterised by a palette of simple and sober materials - polished concrete dyed black for the prefabricated panels of the façade, black lacquered aluminium for the window and door frames, glass for the windows, and steel for the railings - and are marked by a tight rhythmic pattern of regular openings that gives the complex a unified connotation.

Photo Julien Lanoo

LAN Architecture, 40 Housing Units, Paris, France 2014

Photo Julien Lanoo

STARH, Eos, Varna, Bulgaria 2022  The mixed-use project – shops on the ground floor, offices on the first and second floors, residences from the fourth to the ninth floor – is set in a triangular plot that has conditioned the building's plan-volume layout. The marked horizontal course of the structural slabs, the daring overhangs of the prestressed concrete balconies in the acute-angled end – up to 8 m long on the highest floor – the whiteness of the ventilated fibre cement façades lend a plastic and sculptural character to the architecture.

Photo Dian Stanchev

STARH, Eos, Varna, Bulgaria 2022

Photo Dian Stanchev

If the triangle as a symbol of the return to primordial unity and of the relationship with the transcendent belongs, with its respective variants, to all traditions – from the Pythagorean Tetraktys, to the Christian trinity, to the esoteric-Masonic symbolism – sometimes for architects designing a triangular layout can be less evocative. This is the case of interventions set between road junctions and existing buildings, or in general in areas strongly conditioned from a planivolumetric point of view and often considered residual and less attractive to the market just because of their singular conformation.
Although the triangle is widely used in architecture as both a compositional and structural element (think of lattice girders), a triangular plan implies irregular and unusual spaces, sometimes to the detriment of functionality, which might bewilder the designer. 

New York’s Flatiron is named after the site that in the 19th century was commonly known as “Eno’s Flatiron” after its owner. The group of buildings demolished to make way for it actually resembled a flat iron.

However, as the history of architecture demonstrates, works arising from strong constraints have often been emblematic of a design ability in effectively circumventing obstacles, becoming strongly recognisable icons in the urban landscape despite (or thanks to) their peculiarities. This is the case of some of the “flatiron” buildings – gathered in a family named after Burnham’s most famous one overlooking Madison Square in New York City – we propose below which, since 19th-century (Antonelli, Robert jr, Février, Hudec) to contemporary works (Nagy architects, Durbach Block Jaggers Architects, Eastern Design Office, LAN Architecture, STARH) have been able to transform difficulty into opportunity and enhance the dynamic qualities of an imposed triangular shape, be it through rounded corners or accentuated acute edges.

Alessandro Antonelli, Scaccabarozzi House, Turin, Italy 1840 Photo Katell Ar Gow from Flickr

This singular building located in a triangular plot of narrow dimensions, nicknamed "fetta di polenta" (slice of polenta), is the result of the challenge Antonelli undertook to create a dwelling that would fill the limited floor space in height. The construction, raised in 1881, is therefore a sleek volume on a narrow base, characterised inside by rooms conformed to this shape with triangular rooms and custom-made furniture.

Alessandro Antonelli, Scaccabarozzi House, Turin, Italy 1840 Photo Katell Ar Gow from Flickr

David Robert jr, Gooderham Building, Toronto, Canada 1892 Photo Bernard Spragg.NZ on Flickr

Gooderham Building, nestled in a triangular lot between Front Street and Wellington Street in downtown Toronto, is one of the earliest examples of “flatiron” buildings in the city and the country. The massive volume of red brick and copper roofing with dormer windows and gables features eclectic suggestions. 

David Robert jr, Gooderham Building, Toronto, Canada 1892 Photo Will Buckner on Flickr

Daniel Burnham, Flatiron Building, New York, USA 1902 Photo Alberto Giron on Adobe Stock

Considered one of Manhattan’s best known landmarks, the Fuller Building (better known as the Flatiron Building) with its pronounced triangular shape, its 87 m height and 22 floors of office space fills the area at the intersection of Fifth Avenue and Broadway. The building is characterised by limestone and terracotta façades mounted on structural steel frames, in accordance with the type of construction common at the time of the first skyscrapers.

Daniel Burnham, Flatiron Building, New York, USA 1902 Photo travelview on Adobe Stock

Jules and Raymond Février, Esteve Fernández-Caballero, Metrópolis, Madrid, Spain 1911 Photo Luis García su wikimedia commons

The five-storey building between Gran Via and Calle Alcalà in the centre of Madrid, originally designed to house the offices of an insurance group, is characterised by a Beaux-Arts style with fronts supported by imposing Corinthian columns and allegorical sculptures, and surmounted by a slate dome with gold leaf trim and a winged victory. 

Jules and Raymond Février, Esteve Fernández-Caballero, Metrópolis, Madrid, Spain 1911 Photo Diego Delso on wikimedia commons

László Hudec, Wukang Mansion, Shanghai 1924 Foto 钉钉 on wikimedia commons 

The Wukang Mansion is a residential complex that originally housed 63 flats and 30 servants' quarters, designed by Hungarian-Slovak architect László Hudec, a famous name in Shanghai. The unusual wedge shape – due to the conformation of the lot located at the southern end of Wukang Road, at the corner with Middle Huaihai Road – and the 30 m high concrete and masonry volume make it a clearly recognisable element in the context. It has been home to several celebrities over time and still retains its residential function today. 

László Hudec, Wukang Mansion, Shanghai 1924 Photo guineapig33 on Flickr

Durbach Block Jaggers Architects, 5 – 9 Roslyn St, Sydney, Australia 2009 Photo Julia Charles

The triangular shape and small size of the site dictated the plan-volume layout of this four-storey commercial building in Kings Cross, which houses a restaurant on the ground floor and a green roof terrace. The design choices intentionally detach the intervention from the current typology of masonry buildings typical of the area, favouring a plastic volume with a vaguely expressionist flavour, covered with variegated tiles, glossy and matt, white and beige, on which the surrounding environment is reflected.

Durbach Block Jaggers Architects, 5 – 9 Roslyn St, Sydney, Australia 2009 Foto Julia Charles

Sebastian Nagy | architects, Triangolo, Spojovacia, Nitra, Slovakia 2009 Photo Bobo Boška

The triangular apartment building combines the rigorous and essential character of the elevation, with its monomaterial fronts, with the sinuous and lively course of the roof that celebrates the surrounding landscape of Zobor, of the Nitra Plateau and the homonymous river.

Sebastian Nagy | architects, Triangolo, Spojovacia, Nitra, Slovakia 2009 Photo Bobo Boška

Eastern Design Office, On the Corner, Shiga, Japan 2011 Photo Koichi Torimura

Situated in the Youkaichi district, in a mixed-use area – industrial and residential – frequented by immigrants and commuters, the building with seven rental flats is located in a plot long abandoned due to its pronounced triangular shape, considered unattractive to the market. The intervention brings the peculiar urban space back to life, redeeming it through an architectural operation with a strong visual and vaguely surreal impact, amidst intentionally accentuated sharp edges, material textures of stone, cement and glass and lively chiaroscuro effects.

Eastern Design Office, On the Corner, Shiga, Japan 2011 Photo Koichi Torimura

LAN Architecture, 40 Housing Units, Paris, France 2014 Photo Julien Lanoo

The intervention located in the new Clichy-Batignolles mixed development area is a homage to 19th century Paris, to the urban transformation planned by Haussmann in particular, with the new major circulation axes generating new forms and typologies for blocks and buildings at their intersections. The volume fits into a triangular plot, whose geometry it recovers and exploits the spatial potential. The spaces allow for complete reversibility from residential to tertiary use. The façades are characterised by a palette of simple and sober materials - polished concrete dyed black for the prefabricated panels of the façade, black lacquered aluminium for the window and door frames, glass for the windows, and steel for the railings - and are marked by a tight rhythmic pattern of regular openings that gives the complex a unified connotation.

LAN Architecture, 40 Housing Units, Paris, France 2014 Photo Julien Lanoo

STARH, Eos, Varna, Bulgaria 2022 Photo Dian Stanchev

 The mixed-use project – shops on the ground floor, offices on the first and second floors, residences from the fourth to the ninth floor – is set in a triangular plot that has conditioned the building's plan-volume layout. The marked horizontal course of the structural slabs, the daring overhangs of the prestressed concrete balconies in the acute-angled end – up to 8 m long on the highest floor – the whiteness of the ventilated fibre cement façades lend a plastic and sculptural character to the architecture.

STARH, Eos, Varna, Bulgaria 2022 Photo Dian Stanchev