Royal Palace of Brussels

Only in the summer, while the Belgian royal family is vacationing, can the castle be visited. This custom has a long tradition in Belgium's constitutional monarchy. Mostly from the 21st of July to the 3rd of September.

Admission is free.

The Royal Palace of Brussels is the official palace of the King and Queen of the Belgians in the centre of the nation's capital Brussels. However it is not used as a royal residence, as the king and his family live in the Royal Palace of Laeken on the outskirts of Brussels.
The palace is situated in front of Brussels Park. A long square called the Paleizenplein/Place des Palais separates the palace from the park. The middle axis of the park marks both the middle peristyle of the palace and the middle of the facing building on the other side of the park, which is the Palace of the Nation (the Belgian Federal Parliament building). The two facing buildings are said to symbolize Belgium's system of government: a constitutional monarchy.

The Royal Palace (Royal Koninklijk Paleis, French Palais Royal) in the center of the Belgian capital Brussels is the official palace of the King of the Belgians.

It is located opposite the Palace of the Nation at the other end of the Royal Park and symbolizes the constitutional monarchy.

Source: Wikipedia