Historically, Brussels has been predominantly Roman Catholic, especially since the expulsion of Protestants in the 16th century. This is clear from the large number of historical churches in the region, particularly in the City of Brussels. The pre-eminent Catholic cathedral in Brussels is the Cathedral of St. Michael and St. Gudula, serving as the co-cathedral of the Archdiocese of Mechelen–Brussels. On the northwestern side of the region, the National Basilica of the Sacred Heart is a Minor Basilica and parish church and the 14th largest church building in the world. The Church of Our Lady of Laeken holds the tombs of many members of the Belgian royal family, including all the former Belgian monarchs, within the Royal Crypt.