Arthur Gugick is one of my favorite builders when it comes to architectural landmarks. He's built a ton of these at various scales. Of course, the world's architectural landmarks are often religious structures, such as his Saint Peter's Basilica. Saint Peter's is, of course, the main cathedral in Roman Catholicism. It is the heart of the Vatican, where the Pope presides over services on major holidays. Tradition holds that the crypt beneath the altar holds the remains of Peter, one of the twelve disciples of Jesus and the first bishop of Rome.