Tod Williams Billie Tsien’s new bioengineering building at UPENN begs to be different. It’s been hailed by the local architecture critic Inga Saffron as “Philadelphia’s best building in years" and the President of the University of Pennsylvania has dubbed it “The Miracle on 33rd Street". But Skirkanich Hall, a new bioengineering building at the University of Pennsylvania designed by New York architects Tod Williams Billie Tsein, is a building that begs to be different. In its materials and construction it is unlike any building on campus. While most of the buildings on Penn’s campus are steel construction with red-brick cladding, Skirkanich is a concrete building with a shingled glass and aluminum curtain wall, zinc panels and glazed green brick. The 58,000 square foot building sits on a tight site nestled between two 1920's vintage buildings. It houses research laboratories and teaching spaces that are organized around a sculptural staircase.