On our visit in January 2013, the villa containing several mosaics was closed to visitors. According to signage and police guards, accessing this area of the site normally requires buying another ticket at an additional fee (we were allowed to wander without this, but the building used to shelter the remains of the villa was locked). Also access to the area past the "lecture halls" is prohibited due to excavations and lack of foot paths. That said, it's a wonderful archaeological site. The large map just inside the entrance gives a great description of the site's layout and you can wander into and around the amphitheatre. The theatre itself is small -- this is not the Roman colosseum -- but was part of a a remarkably advanced urban complex that included artisanal workshops, baths, auditoria, etc.
Accessing the amphitheatre requires climbing down stairs.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.