The Colosseum, a symbol of ancient Rome and one of the most iconic landmarks in the world, is not owned by the Catholic Church. It is, in fact, a property of the Italian government and falls under the authority of the Ministry of Cultural Heritage and Activities.
The structure, which dates back to AD 70-80, was primarily used for gladiatorial contests and public spectacles. Its ownership has changed hands multiple times throughout history, but it has always remained a public monument. The Catholic Church has a significant historical relationship with the site, particularly because of its ties to Christianity and the many martyrs who are said to have died there. However, this does not equate to ownership.
The Colosseum is now managed by the Colosseum Archaeological Park, which oversees its maintenance and preservation. Although the Catholic Church may conduct events or services in the vicinity, especially considering its historical significance, it does not hold any legal ownership over the Colosseum itself.