The Royal Palace of Caserta  is a former royal residence in Caserta, southern Italy, constructed by the House of Bourbon-Two Sicilies as their main residence as kings of Naples. It is the largest palace erected in Europe during the 18th century. In 1997, the palace was designated a UNESCO World Heritage Site; its nomination described it as "the swan song of the spectacular art of the Baroque, from which it adopted all the features needed to create the illusions of multidirectional space".

In terms of volume, the Royal Palace of Caserta is the largest royal residences in the world with over 1 million m³ and covering an area of 47,000 m².

The palace has 5 floors, 1,200 rooms, including two dozen state apartments, a large library, and a theatre modelled after the Teatro San Carlo of Naples. A monumental avenue that would run 20 kilometers between the palace and Naples was planned but never realized. 

The palace has a rectangular plan, measuring 247 × 184 m, and the four sides are connected by two orthogonal arms, forming four inner courts. Each floor measures approximately 47,000 m2 (505,904 sq ft), but considering the five floors, the whole palace measures 235,000 m2 (2,529,519 sq ft).

Caserta is by far the largest royal palace in the world in terms of volume, with more than 2 million m³ (70 million cu ft). Behind the façades of its matching segmental ranges of outbuildings that flank the giant forecourt, a jumble of buildings arose to facilitate daily business. The palace encloses four courts that feature what scholars describe as well-proportioned interior that evoke a monotonous dignity, unique in its time. 

According to en.wikipedia