Rome's birthday, known as Natale di Roma, falls on 21 April, and this year the city marks 2,775 years since its legendary founding by Romulus in 753 BC. One spectacular event that occurs in Rome's birthday is the Dies Natalis phenomenon at the Pantheon.

Each year on this date the midday sun enters the oculus of Rome's Pantheon and creates a disk of light that centres perfectly on the entrance doorway. At that exact time, the emperor would enter the temple, his body bathed in the intense golden sunlight. In 2020 Italy's culture ministry released a video of the phenomenon which it described as "one of history's first great special effects."