Many historical structures stand in Maribor. Of the remains of city walls surrounding the old downtown, the most prominent are the Judgement Tower, the Water Tower, and the Jewish Tower. Maribor Cathedral was built in the Gothic style in the 13th century. Maribor Synagogue was built in the 14th century, and is the second oldest synagogue of Europe. Today it serves as a centre for cultural activities. Other prominent Medieval buildings are Maribor Castle, Betnava Castle, and the ruins of Upper Maribor Castle on Pyramid Hill. Town Hall was constructed in the Renaissance style, and the Plague Column in the Baroque style.