After Saint Peter's Basilica in Rome, this is one of the most important and impressive cathedrals in Catholicism. It is a masterpiece of the Gothic styles and a textbook example of a number of architectural attributes, most strikingly, its flying buttresses. This is also where Napoleon crowned himself emperor of France in 1804. Even its location is significant, being constructed on an island in the heart of Paris, and also on the ruins of an ancient Roman temple honoring the god Jupiter. Pope Alexander the Third personally laid the first foundation stone for the new cathedral which replaced two early Christian churches. In spite of this ancient beginning, one of Notre Dame's most prominent features is a recent addition. The grand spire was erected in the 1800's during a renovation by E.E. Voillet-le-Duc, but still lives in harmony with the two towers on the western facade that were put up between 1210 and 1250. Even though these towers are described as "massive" they are still incomplete. At 223 feet they are huge, but like many cathedrals of Europe, they remain unfinished lacking spires of their own.