About a year ago, a relative sent me a box of hundreds of slides dating back to the 1950s, documenting much of her life with her husband and kids and travels. She'd been contemplating throwing them in the trash, since nobody else seemed interested. While going through the box, I found a number of images from the 1958 Brussels World's Fair, also known as "Expo 58", which was the first major World Fair since the end of WWII. Nearly 15,000 workers spent three years building the 2 km2 (490 acres) site on the Heysel/Heizel Plateau, 7 kilometres (4.3 mi) north-west of central Brussels. Many of the buildings were re-used from the 1935 World's Fair, which had been held on the same site.
First up is this neat photo of the ultra-modern German Pavilion; an article on Reddit stated: International-style architecture and modernist exhibition design were mobilized as instruments of cultural soft power to convey these multiple messages. Hans Schwippert of the postwar German Werkbund choreographed exhibition design, deploying the miracle economy's modern consumer culture to celebrate the emergence of a post-Nazi society. Egon Eiermann, aided by Sep Ruf, designed the International-style pavilion, celebrated as the architecture of postwar modernity, but in fact derived from a precedent in Third Reich industrial architecture.

Next is an exterior of the Austrian pavilion. Architect Karl Schwanzer, for instance, in his Austrian pavilion proposed a main exhibition building as a square, translucent box carried by four central columns, raised one story above the ground. The building had a square plan and a structure in welded steel. This pavilion was shaped by a hollow square plan and its exhibition floor cantilevered outwards to leave a “floating” impression. At night, the translucent façades lit up from the inside, which, together with the light tubes in the ceiling of the ground floor, turned the pavilion into a giant lampion (lantern) with an almost weightless outlook.

This next photo is from the interior of the United States pavilion. From an online article: The United States pavilion at the 1958 Brussels World's Fair, also known as Expo 58, was a large, architecturally complex space that featured a variety of exhibits and activities. Designed by Edward Durell Stone, the pavilion was made up of four buildings, including one with railroad boxes on stilts, and had a translucent, bicycle wheel-shaped roof.
The pavilion included a 360° movie called America the Beautiful created by Walt Disney Productions. The movie was shown in a specially designed round theater with a white ceramic grille facade. The pavilion also featured a three-dimensional New York City streetscape designed by Robert Brownjohn.
(It) hosted a fashion show, a performance by the Seventh Army Symphony Orchestra, and an electronic computer that demonstrated historical knowledge. It also displayed popular American treats like ice cream and Coca-Cola.

Here's the inside of the USSR pavilion: The main themes of the Soviet Pavilion were space exploration (with the Sputnik satellite as the core of the exposition), the celebration of heavy industry, and the fast economic development of the USSR under the communist regime. Among other themes, a significant part of their exhibition was dedicated to the emancipation of women and their successful employment in all professional spheres of the USSR, which was a rather progressive subject at that time. Slick propaganda leaflets in English provided general information about the country, boasting of increased industrial production in comparison with capitalistic countries, and focused on such subjects as the Soviet democratic system, the great social benefits for all citizens, and free education and childcare systems. Hey, I am merely quoting what somebody else wrote!

Here's a stunning structure for Philips corporation: It was a modernist pavilion... commissioned by electronics manufacturer Philips and designed by the office of Le Corbusier (and) was built to house a multimedia spectacle that celebrated postwar technological progress.
The reinforced concrete pavilion is a cluster of nine hyperbolic paraboloids in which Edgard Varèse's Poème électronique was spatialized by sound projectionists using telephone dials. The speakers were set into the walls, which were coated in asbestos, giving a textured look to the walls. Varèse drew up a detailed spatialization scheme for the entire piece, which made great use of the pavilion's physical layout, especially its height. The asbestos hardened the walls, which created a cavernous acoustic. As audiences entered and exited the building, Xenakis's musique concrète composition Concret PH was heard. The building was demolished on 30 January 1959.

And finally, here's a photo of an interesting souvenir pin from the Fair that is in my collection; the asymmetrical star was the symbol of Expo 58. I believe (but am not certain) that the silhouetted building inside the star could represent the Kremlin, so this might have been from the USSR pavilion. I've seen the graphic of the stylized person holding the Fair symbols on a poster, but have no further info about it.
I hope you have enjoyed these photos from Expo 58!