The Baths of Caracalla in Rome were popular 1,800 years ago and still are.
The demand for guided tours has been so great that the site is once again open for night tours.
The biggest and best preserved temple of Mithras in Rome, which is normally closed to the public, is now being specially opened.
No more than 30 visitors are admitted at a time to admire the 37-metre-high ruins.
Maurizio Pinotti, Technical Supervisor of Caracalla Baths complex says, "We decided to replicate the initiative with evening openings twice a week. The route takes visitors through the entire area above ground, to then descend into the underground tunnel and the temple of Mithras, which is being specially opened for this event and marks the end of the visit."
The Baths boast highly efficient water supply, heating and drainage systems, which made them an architectural wonder operated by dozens of slaves.
The 75 minute guided visits in Italian and English take place every Tuesday and Friday until 02 October.