As of my last knowledge update in September 2021, I can provide you with a list of some of Rome's top monuments and attractions. Please note that the popularity of attractions can change over time, and new ones may have emerged since then. I recommend checking the most recent information and reviews when planning your visit to Rome in 2023. Here are some iconic attractions that were popular in 2021:

  1. Colosseum tour: This ancient Roman amphitheater is a symbol of Rome and a must-visit historical site. It's best to book tickets in advance to skip the long lines.

  2. Roman Forum: Adjacent to the Colosseum, the Roman Forum is a fascinating archaeological site showcasing the heart of ancient Rome's political and social life.

  3. Pantheon: A remarkable temple-turned-church with a stunning dome and a well-preserved interior. It's a marvel of ancient engineering.

  4. Vatican City: Home to St. Peter's Basilica, the Vatican Museums, and the Sistine Chapel, Vatican City is a must-visit for art, history, and religious enthusiasts.

  5. Trevi Fountain: One of the most famous fountains in the world, the Trevi Fountain is known for its intricate design and the tradition of tossing a coin over your shoulder to ensure your return to Rome.

  6. Spanish Steps: A grand staircase leading to the Trinità dei Monti church, it's a popular spot for people-watching and taking in the city views.

  7. Piazza Navona: A lively square with beautiful Baroque architecture, it's a great place to enjoy street performances and dine at outdoor cafes.

  8. Villa Borghese: A large park offering a peaceful escape from the city, with beautiful gardens, museums, and a lake where you can rent rowboats.

  9. Castel Sant'Angelo: Originally built as a mausoleum for Emperor Hadrian, this castle has served various purposes over the centuries and offers great views of the city.

  10. Capitoline Hill and Museums: One of Rome's seven hills, it houses a collection of art and archaeological museums, as well as the stunning Piazza del Campidoglio.

  11. Piazza Venezia: Dominated by the massive Monument to Vittorio Emanuele II, this central square is a hub of traffic and history.

  12. Basilica of San Clemente: This unique church has multiple layers of history, with a medieval basilica built on top of an earlier Christian church, which is in turn built over a Roman house.

Remember that Rome is a city rich in history and culture, and there are countless more attractions, museums, churches, and hidden gems to discover. Depending on your interests, you may want to explore different neighborhoods, art galleries, and local markets to get a deeper sense of the city's character. Be sure to check for any updates, ticket information, and visitor guidelines before your trip in 2023.