The Colosseum in Rome is open almost every date of the year. It is closed only on the 1st of January and the 25th of December. The rest of the year, Colosseum is open for visitors. Colosseum opening hours are seasonal and depend on the time of the year. The last entrance is one hour before the closing time.
Regular Colosseum opening time is from 08:30h
The opening time of Colosseum on June 2nd is from 13:30h because of the Italian National Day
During the winter, it usually closes at 17h, and in the rest of the year, it can be open until 19h, depending on the exact time of the year. Except for December 25th and January 1st, the Colosseum is open every day of the year.