Visit windmills and traditional crafts at Zaanse Schans or tulip fields at Keukenhof (Keukenhof open mid-March–mid-May); check seasonal opening times before booking.
Marvel at the Vatican’s collections and Michelangelo’s Sistine Chapel ceiling; museums usually open 9:00–18:00 (closed Sundays except last Sunday of month) so early entry is recommended with pre-booked tickets.
Visit St. Peter’s and, if you like, climb the dome for sweeping views; basilica open 7:00–19:00 but dome access has separate hours and fees—check on-site.
Enjoy a last passeggiata through central Rome, toss a coin in Trevi and relax at the Spanish Steps; public spaces accessible anytime but are busiest late afternoon/evening.