The cell was constructed atop slave quarters.[112] The handcuffs used by police in Cambridge, Massachusetts, to arrest African-American Harvard University professor Henry Louis Gates Jr., in 2009.[112] President Barack Obama's 2008 presidential campaign office from Falls Church, Virginia.[113] The Moog synthesizer and MPC beat machine used by hip-hop producer J Dilla.[114] Several paintings and pieces of terracotta sculpture from the Barnett-Aden Collection, donated by BET founder Robert L. Johnson.[115][lower-alpha 8] Several items from the São José Paquete Africa, a sunken slave ship excavated off the coast of South Africa in 2015.