The Old Lapau, formerly known as the Lapau, is a historical building in Bandar Seri Begawan, Brunei. It was the former lapau or royal ceremonial hall prior to the existence of the current Lapau building. It was also where the Constitution of Brunei was promulgated in 1959. It now houses a museum pertaining to the Constitution.

The Lapau, also known as the Royal Ceremonial Hall, is a ceremonial hall in Bandar Seri Begawan, Brunei. It is where the royal ceremonies, state investiture and some state events are traditionally held. It was the place where the present Sultan of Brunei, Sultan Hassanal Bolkiah, was crowned in 1968.