That the most popular place in Italy for having you pocket picked is on the number 64 bus in Rome? Its route runs between the Stazione Termini and St Peter's Square. Thieves know that it is routinely packed with tourists.
The easiest way not to look like a tourist? Local police suggest wearing a pair of over-sized sunglasses.
That Michelangelo carved David from a pure block of marble, but the biblical David was Jewish and therefore circumcised. The David portrayed by Michelangelo's statue is not. The sculptor (as well as his model) was Roman Catholic and he simply "drew what he knew." David is 16 feet, 10 inches tall.
That the Pieta (found in St. Peter's Basilica) is the only work by Michelangelo that the artist never signed. Because he overheard someone attribute the piece to another sculptor, he snuck into the chapel at night and carved his name across Mary's chest to eliminate any question.