one room�presumably under or behind the arch�was more than 36 m (110 ft) high. The massive barrel vault covered an area 24 m (80 ft) wide by 50 m (160 ft) long, and was the largest vault ever constructed in Persia. It is still "the largest unreinforced brick vault in the world."
Archaeology
A German Oriental Society and University of Pennsylvania team led by Oscar Reuther excavated at Ctesiphon in 1928�29 and 1931�32, mainly at Qasr bint al-Qadi on the western part of the site.
In the late 1960s and early 1970s, an Italian team from the University of Turin directed by A. Invernizzi and G. Gullini worked at the site, mainly doing restoration at the palace of Khosraw II
