The power of tradition : spolia in the architecture of St. Peter's in the Vatican / Lex BosmanMarble past, monumental present : building with antiquities in the mediaeval Mediterranean / by Michael GreenhalghConstantinople to Córdoba : dismantling ancient architecture in the East, North Africa and Islamic Spain / by Michael GreenhalghSpolia in fortifications and the common builder in late antiquity / by Jon M. Frey