The world's largest functioning royal palace by floor space is the Royal Palace of Madrid in Spain, with 135,000 square metres (1,450,000 sq ft) of floor space and containing 3,418 rooms.

The title of "largest palace" depends on how you measure it: by floor area, the Palace of the Parliament in Bucharest, Romania, is the largest administrative building and palace, boasting over 3.5 million square feet of floor space. However, in terms of a royal residence still in use, the Istana Nurul Iman in Brunei holds the record with 2.15 million square feet, featuring 1,788 rooms. If measuring by the total area of the enclosed grounds, the Forbidden City in Beijing, China, is the undisputed champion, covering 178 acres (7.7 million square feet) and containing nearly 1,000 buildings. Other notable contenders include the Louvre Palace in Paris (now primarily a museum) and the Hofburg Palace in Vienna. In 2026, these sites remain major cultural hubs, representing the peak of architectural ambition and the vast historical wealth of the empires that constructed them.