Siak Regency is the number two richest district in Riau after Bengkalis Regency. The main export of Siak Regency is petroleum which finally can deliver it to become the second richest regency in the province. On the other hand, the regency is currently boosting the tourism sector to attract more visitors. As Siak was once the house of the Sultanate of Siak Sri Indrapura, the regency contains remnants of the sultanate that is still well-preserved, such as the Siak Sri Indrapura Palace. The palace complex has an area of about 32,000 square meters consisting of 4 palaces namely Istana Siak, Istana Lima, Istana Padjang, and Istana Baru. Each of the palace including "Siak Palace" itself has an area of 1,000 square meters. The palace contains royal ceremonial objects, such as a gold-plated crown set with diamonds, a golden throne and personal objects of Sultan Syarif Qasyim and his wife, such as the "Komet", a multi-centennial musical instrument which is said to have been made only two copies in the world. Presently, the "komet" is still functioning and is used to play works by composers such as Beethoven, Mozart and Strauss. Siak is also home to the tomb of Sultan Syarif Kasim II, the last Sultan of Siak.