“The visits can be fraught. ‘Sometimes people say: ‘The Germans have all our heritage! They stole it!’’ said Zoya Masoud, 27, who led the Arabic-language tour that afternoon at the Museum of Islamic Art, which is part of the Pergamon Museum and filled with treasures from empires past. Often, the visitors say the art is probably better off in Berlin because so much in Syria has been destroyed by the war and the Islamic State, Ms. Masoud said.”