The title of the "world's largest palace" is both difficult to award and controversial, as different countries use different standards to claim that their palace is the largest in the world.The title of "world's largest palace by area enclosed within the palace's fortified walls" is held by China's Forbidden City complex in Beijing, which covers an area of 728,000 square metres (180 acres).

The sanctuary, which lay between today's piazza della Pilotta and the large square facing Quirinal Palace, was built by Caracalla on the western slopes of the hill, covering over 13,000 m 2 (3.2 acres), as its sides measured 135 by 98 m (443 by 322 ft). It was composed by a long courtyard (surrounded by a colonnade) and by the ritual area, where statues and obelisks had been erected.