The church you see today was built between 1150 and 1250. One account suggests that a great fire in 1150 destroyed much of Cologne, and that the earlier church may have been lost with it. Whatever the trigger, the result was a grand new building in the style of the late Hohenstaufen era, known as Staufen Romanesque. Look for the heavy pillars, massive walls and round arches over the windows and portals. Romanesque means Roman-like, and those rounded arches are the clue. The big square crossing tower is flanked by four smaller towers, which gives the top of the church a crown-like effect. Now look at the eastern end, where three rounded apses curve around the crossing in a trefoil, or clover-leaf, plan. This is called a triconch. There is also a design principle at work: the forms become more complex as you move from west to east, and from the base of the building up to the highest level of the tower. Inside, you can also find Baroque elements added after restorations in the eighteenth century, so different eras share the same space.