|"Is this all real? Or has this been happening inside my head?"
The topic of this article is of a real-life subject that has been mentioned "in-universe" in a canon source. The Harry Potter Wiki is written from the perspective that all information presented in canon is true (e.g., Hogwarts really exists), and, as such, details contained in this article may differ from real world facts.
In 1754, the Coliseum was selected as the finishing line in a broom race from Aberdeen to Rome between famous fliers Torquil McTavish and Silvio Astolfi, and government representatives and supporters gathered there to await their arrival. However, just as the pair were seen flying toward the ancient amphitheatre, a clash broke out between rival factions of fans. During the fight, an explosion was somehow set off, leaving the Coliseum in ruins. Orabella Nuttley stepped forward and repaired a few columns with the Mending Charm she had invented. Amazed, the assembled ministers asked her to teach them how to perform it, and the damage to the Coliseum was undone by the time that Muggles woken up by the sound of the explosion arrived at the scene.