Frei Otto's and Gunter Behnisch's 1972 Olympic Games Tent. The entire roof is a sort of plexiglass held up as a tension net or tensegrity.
We may have hopped a few... "barriers."
This is year old student housing that I found really interesting. In an area no bigger than 4 or 5 acres there was enough housing for 1,200 people... so about 300 people per acre. That's the same density as Hong Kong but done with dual story single residences.
It's all precast concrete. The units are small, most have green roofs. The pathway between the buildings in no more than 2 m wide.
BMW Welt (world) by Coop Himmelblau.
Allianz Arena by Herzog and de Meuron. The outside is inflated bubbles that can be lit from the inside and change color.
My crazy Brazilians in front of the Munich Rathaus (town hall - I know, the irony). They're a blast.