See the remarkably preserved Roman temple with its oculus and grand dome; a must for architectural history. Open daily — check seasonal hours (generally 9:00–19:00).
Pre-booked timed-entry to avoid lines; see Raphael Rooms and Michelangelo's Sistine Chapel — museums generally open 9:00–18:00 (closed Sun except last Sun).
Tour the Colosseum's arena/levels with pre-booked tickets to skip long lines and learn its gladiatorial history; opening hours generally 8:30–17:00 (seasonal).
Wander the heart of ancient Rome among temples and ruins for context on imperial politics and daily life; combined ticket with Colosseum usually valid same day.