Paul M. Farber is the Artistic Director of Monument Lab and Lecturer in Fine Arts and Urban Studies at the University of Pennsylvania. He is the author of "A Wall of Our Own": An American History of the Berlin Wall.   Ken Lum is the Chief Curatorial Advisor of Monument Lab and an Artist and Professor and Chair of the Department of Fine Arts at the University of Pennsylvania.  He is co-author of Shanghai Modern: 1919 - 1945.