LEGO Architecture: Transamerica Pyramid
San Francisco's Transamerica Pyramid is an 853 ft. building consisting of 48 stories. The model is one of the shortest in this exhibit, measuring only 4'0" tall. It contains 4,800 pieces and took 20 hours to design and 40 hours to build.
Photo of LEGO Architecture exhibit by Wally Bahny for TechRepublic
I believe the open areas are actually parking. Odd, but there's parking spaces with cars in them all around the outside of the building. Not sure how they get up there, I always assumed some sort of elevator.