The Duomo in Milan is a beautiful Cathedral. Cardinal Martini died a day before. The people were lining up all across the city to pay him their last respect.
The St. Pieter Basilic is the Vatican Church. It is such a rich environment in every aspect.
Forget about Pompei. Ostia Antica is at least equally impressive but gets just a fraction of the visitors Pompei serves every day. It is just like walking through a Roman city 2000 years ago.