A small theatre was reported by Lanciani in 1868 as forming part of the Imperial Palace (26). Only the outline was seen, it had not been fully excavated. Lanciani saw the stage, decorated with niches, and remains of the seats. On his plan it is shown within the limits of the palace.
Geophysical research (Keay 2005) could not confirm this feature, but a semicircular or circular feature was found not far away (external diameter c. 35 m., inner circle c. 28 m.). This coincides with a similar structure drawn by Gismondi on the plan that is used here.