Mies van der Rohe's marble-covered Barcelona Pavilion was designed for the 1929 Barcelona International Exhibition as Germany's national pavilion. It was disassembled the next year, but reconstructed in the 1980s because of its architectural and historical significance.
I think the only place that people tend not to explore too much when they visit Barcelona is the Montjuïc area, which is really great.
There’s the CaixaForum. Right now they have an Egyptian exhibit, and it’s really good. Right in front of that is the Mies van der Rohe pavilion. He was the founder of the Bauhaus movement, and is my favorite architect. He’s the one who coined the expression “Less is more,” and that’s the house. He’s just such a minimalist. The pavilion was built for the Barcelona International Exhibition, and they just kept it up.
Ascend to the gardens of Montjuïc via escalator and you'll find hilariously opulent waterfalls--and a great view.
Then there are the gardens of Montjuïc, and on top you have such a great view of everything in Barcelona, down to the sea. All the gardens have names. Then on top of everything you have the Olympic rings, and everything that was built for the ’92 Olympics. There’s hours of things to do there, and it’s not as crowded. You can see the whole city. On the weekends, they have Piknic Electronik, on a hillside. They have food trucks that come in, and electronic music. After the summer is over, they have Brunch Electronik instead.
Then, on the walk down from Montjuïc, down the Parallels, there are a whole bunch of restaurants and cafes. It’s a good exploration.