Paul Andreu: La Grande Arche de Defense
Architect Johann Otto von Spreckelsen was actually the first one to draw up the plans for it with the help of engineer Erik Reitzel. Construction began in 1985, but Spreckelsen decided to retire in 1986 and passed on the responsibilities to Andreu. Some say that the monument looks like a hypercube (a 4-dimensional object) being projected onto the 3-dimensional world. Which I think is really cool. I was always intrigued how a hypercube was supposed to look in 3D instead of the 2D drawings that I would make.