On a site once 25 times the size of the Colosseum, only 30 rooms of the 250-room palace can be visited, and by guided tour only.
Visitation to the site became restricted after a security threat.
mnli hypothesis: Visitation to the site became restricted after a security threat. premise: On a site once 25 times the size of the Colosseum, only 30 rooms of the 250-room palace can be visited, and by guided tour only.