The hammerbeam roof, a mediaeval type of stepped wooden architecture designed for spanning wide spaces, is a feature of which ancient English building?
What type of building is famous in Milan, Venice, Florence, Seville, Paris, Chartres, Amiens, Rheims, Cologne, Mainz and Trèves?
What is the meaning of the name of the great building in Istanbul, built in the early 6th century as a Christian church, subsequently becoming a Muslim mosque, a secular museum and a Muslim mosque again?
