Pompeii in southern Italy, one of the best-known Roman sites, was also closed, The Local.it reported.
Employees of the Ministry of Cultural Heritage and Activities say overtime is being paid months late and they are also angry about layoffs. They met with officials Friday and Antonia Pasqua Recchia, the ministry's secretary general, said later there had been progress on timely pay and other issues.
Workers protested outside the ministry as well.
The Colosseum, which was closed for two days last week because of employee actions, remained open Friday after the ministry promised its employees full payment of overtime. The Castel Sant'Angelo, the massive burial site of the Emperor Hadrian, and the National Gallery of Modern Art, among others, were shut down.