Belgium's Atomium building, representing an iron atom magnified five billion times, celebrated its 50th anniversary on Thursday.
The structure, touted as the "most astonishing building in the world", was built for the 1958 World's Fair, held in Brussels.
The anniversary was marked by fireworks, concerts, exhibitions and film showings, writes AP.
The building has experienced an upturn of late, with dwindling visitor numbers turned around by a US$43m facelift in 2006, attracting one million visitors in 18 months.
The Atomium features a permanent exhibition of the 1950s, temporary art shows and a gourmet restaurant.
By staff writer