Crafted from steel, glass and marble, the Barcelona Pavilion has a history as rich as the materials used to construct it. It was originally designed as the German national pavilion for the Barcelona International Exhibition held in 1929, but its purpose was only temporary. As such, it was torn down in 1930. Despite not existing physically, this significant masterpiece by influential architect Ludwig Mies van der Rohe lived on in memory, and was finally reconstructed in 1986. It is open from 10am daily and you can visit this architectural marvel for only 5 euros, or for free for those under 16.