Characteristic for Mühlhausen's buildings is the predominant use of one kind of material – Travertine. It was found near the city in large quantities and is both light and solid, so that the Gothic churches with their filigree masonries and other important buildings could be built relatively cheaply. Nevertheless, many older citizens' houses were half-timbered constructions, with only the ground-floors made of stone. Sights and architectural heritage Churches and synagogue Mühlhausen is primarily known for its large number of intact Gothic churches: Inside the inner city walls St. Blaise's Church is the main church of the medieval Old Town at Untermarkt. It was built during the 13th century in early-Gothic style and is one of the most important 13th-century church buildings in Germany. It was first mentioned in 1227. The Teutonic Knights, owners of the church, had it expanded after 1270 using architects/builders from Maulbronn and Walkenried. Johann Sebastian Bach worked here in 1707–1708 as organist. Today, it is the main Lutheran parish church of Mühlhausen. St. Mary's Church is the main church of the medieval New Town at Obermarkt. It was built in the early 14th century in high-Gothic style and is Thuringia's second-largest church after Erfurt Cathedral, sporting Thuringia's highest steeple (). In 1975, the church was deconsecrated and is used as a museum today. All Saints Church at Steinweg was built in the late 13th century and has been a museum since 1989. St. Anthony's Chapel at Holzstraße was built in the 13th century and is a hostel today. Corn Market Church at Kornmarkt was built as a Franciscanian monastery c. 1250. The monastery was abandoned in 1568. In 1702–22 the church was redesigned in the baroque style. The last service was held here in 1802 after which the church became a warehouse. Since 1975 it has been used as a museum. St. James's Church at Jakobistraße was built in the 14th century and hosts the city library today. St. Kilian's Church at Kiliansgraben was built during the 14th/15th century and hosts a theatre today. St. Peter and Paul's Church between Steinweg and Mönchgasse was the church of the Dominican monastery, built in the early 14th century and demolished after a fire in 1689. Today, there are only a few walls remaining. Outside the inner city walls St. George's Church at Sondershäuser Straße was built in the 14th century and is a Protestant parish church today. St.