9The Pantheon in Rome, Italy

Originally the temple to the Roman pantheon of gods, the Pantheon was made into a church in the 7th Century CE with the Roman deities in the alcoves in the building replaced with saints and other biblical figures.

It is over 180 metres long and the largest Catholic Church in the world. Located in the Vatican City, it is one of the four largest basilicas in Rome and the main pontifical church. As a result, the Pantheon is one of the best-preserved buildings from ancient Rome. The building is built from a material that seems similar to modern-day concrete which has lasted incredibly well. The floors are still original, and while the doors aren’t original, they are also from ancient times.