Built in 1851 in London according to the design of the botanist and greenhouse builder Joseph Paxton, the Crystal Palace a milestone in the history of architecture, not only because of its monumental scale and the technical innovations involved in its construction, but also because it was the setting for the first World's Fair. The greenhouse-inspired construction was completed in a very short time thanks to the modular assembly system of iron and glass elements carried out directly on site. After the event, the Crystal Palace was dismantled and rebuilt in 1852 in south London's Sydenham Hill. Various new uses were attempted over the years: from the Festival of Empire in 1911 to the Imperial War Museum from 1920 to 1924. However, it was ruinously destroyed by fire on 30 November 1936.

Expressing the aesthetics of the Belle Époque, the complex was built for the 1900 Universal Exhibition in Paris. The steel and glass structure features a majestic façade decorated with Ionic columns and gigantic bronze statues. Throughout the 20th century, the Grand Palais hosted events, fairs and exhibitions, and even today art exhibitions of major importance are held in the Galeries Nationales du Grand Palais. On the south-west side there is the Palais de la Découverte, a museum opened in 1937 and dedicated to science. 

The temporary pavilion was built for the International Exhibition of Decorative Arts in Paris in 1925, as a full-scale prototype of a standardised dwelling composed of mass-produced elements. The building was conceived as a modular prototype cell to be repeated at the urban scale of the Immeuble-villas, with the aim of satisfying housing needs through quick, affordable but qualitative solutions. The original pavilion was dismantled but, in 1977, a replica was reconstructed in Bologna by architects Giuliano Gresleri and José Oubrerie: located near the exhibition complex designed by Kenzō Tange, the building is used as an exhibition space.

The work, realised for the Exposition des Arts Décoratifs in Paris, was conceived as a manifesto of Russian Constructivism in Europe. The building was characterised by a rectangular layout and a wood and glass structure; the volume was decomposed into two triangular prisms, separated by a slit occupied by the staircase-bridge, on which sloping roof panels intersected. The centrepiece of the exterior space was the tower that supported the CCCP inscription.

Designed and constructed for the 1929 World's Fair in Barcelona, the iconic building expresses some of the fundamentals of Mies van der Rohe's thinking: the open plan, the rigorous structural grid, the use of high-quality materials and the continuity between exterior and interior. The building is characterised by a clear orthogonal layout and is covered by a flat roof that seems to float in the air, as it is supported by slender cruciform pillars On the outside, the building's ethereal image is reflected in two water pools: in the smaller one, Georg Kolbe's bronze sculpture ("Der Morgen") emerges from the water as lightly as the building stands on its travertine podium. Inside walls cladded with large format stone panels of green marble, travertine, onyx give rhythm and character to the space. The structure, conceived as temporary, was demolished after the event and rebuilt philologically between 1983 and 1986. Today it hosts exhibitions and art installations and is the venue for the prestigious EU Mies Award.

Designed by Le Corbusier and the Greek engineer-musician Jannis Xenakis for the Brussels Expo of 1958, the reinforced concrete pavilion consisted of a group of nine hyperbolic paraboloids and housed the installation "Le poème électronique", consisting of a combination of lights, projections and music (composed by E. Varèse and Xenakis himself) and celebrating the new electronic age. The building was demolished in 1959.

The flagship of Madrid's rationalist architecture, the Pabellón de los Hexágonos, designed by architects José Antonio Corrales and Ramón Vázquez Molezún for the Brussels Expo in 1958, which also won the Gold Medal at the time, was a manifesto of modernity. The building consists of 130 hexagons made of terracotta bricks, glass and aluminium, covering 3,000 square metres. Moved to Madrid’s Casa de Campo in 1959, , the Pavilion hosted fairs and exhibitions, before slowly falling into disuse for almost fifty years. It has recently been reopened to the public for temporary exhibitions. 

The structure was originally built as a US pavilion for the 1967 Expo. The geodesic dome, designed by Buckminster Fuller and supported by an intricate network of steel tubes, is still an iconic landmark in the urban landscape. Today, the complex houses an environmental museum.

The pavilion was a milestone in the field of construction engineering, turning the spotlight on tensile structures and their not only technical but also figurative properties. The work consisted of a tensile structure inspired by soap bubbles, generated by the connection between suspension points and anchors. The great potential of this system was in the speed of realisation and lightness: the steel structure and membrane weighed only 150 tonnes, about one third to one fifth of the weight of the traditional materials used at the time.

The building was meant to represent Switzerland's skills and inventiveness, precision and love of beauty. A 21 m high and 55 m wide steel structure, resembling a stylised tree, housed exhibition spaces and a restaurant. With 32,000 glass spheres that shone in the sunlight and lit up like bulbs at night, the tree of light displayed a radiant and festive character.

At the Universal Expo in Seville, Italy presented the pavilion designed by Gae Aulenti and Pierluigi Spadolini, a six-storey complex distributed over an area of 6,000 square metres. The interior layout includes a large full-height central gallery, with exhibition rooms arranged on both sides of it and on various levels, offices, a roof garden, two restaurants and services. A refined lighting design by Studio Piero Castiglioni aimed to emphasise the image of the building as a “lantern” in the night, also focusing on the “Lumbreras”, the glass surfaces on the gallery roof. The building is among the best preserved in the Cartuja area and today houses offices.

MVRDV's project developed a proposal for the theme "Holland Creates Space", revealing the potential of a country that had always faced land scarcity. The work took the form of an autonomous ecosystem with its own natural cycles, in which six typical Dutch landscapes (including a forest on the third floor) were stacked in a tower building. After twenty years of disuse, MVRDV's redevelopment project provided for the conversion of the exhibition pavilion into an office building and co-working space.

The monolithic white steel construction is arranged in a double spiral layout and is characterised by continuous spatial sequences, to be experienced on foot or by bicycle, thanks to the 1500 bicycles provided at the entrance, to get a taste of the ecological Danish lifestyle. Once across the threshold, the statue of the Little Mermaid, moved for the first time to a location different from its original site, dominates the scene, surrounded by a pool of water evoking the sea in Copenhagen harbour.

The pavilion was conceived as a continuous 2, 000-square-metre landscape enclosed by walls clad in precast white concrete panels and featuring ten orchards, one for each of the country's major native fruit trees, divided and intersected by covered exhibition areas featuring archaeological artefacts from the country's ancient cultural heritage. Once dismantled, the pavilion was transferred to Bahrain to be reconstructed and used as a botanical garden.

The Expo 2020 area is destined, after the end of the event, to become a multifunctional service and infrastructure district, in which many pavilions will be preserved. Among these, there is Alif, the Mobility Pavilion, named after the first Arabic letter and, in extended form, meaning "beginning" (the beginning of a future based on tools and systems to facilitate the quality of life): with its sinuous forms and shell clad in stainless steel sheets interspersed with curvilinear bands of glass, it winks at futurism and evokes the idea of movement. The pavilion, distributed over five floors above ground and two underground, was designed with scrupulous attention to sustainability, from the self-shading conformation to the photovoltaic system, to the reflective shell.