Located at Piazza della Repubblica, on the same site as Museo Nazionale Romano. An informative documentary film presented upon entering details what the Diocletian Baths used to look like, with magnificent rich detailing, marble structures and statues. Although much of the original details are no longer there, the structure has been maintained. It is interesting to learn that the beautiful adjacent basilica was built using part of the old baths’ structure. We liked the opera presentations at the baths that usually take place at least once a week in summer. It is usually not a full opera but rather the most beautiful parts. The program is under Diocleziano all’Opera, you can check their site for prices and conditions (sometimes if you buy the ticket to the museum you can see the presentations)