Mount Fortress

Built in conjunction with the Jesuits from 1617 to 1626, this was the city's principal military defence structure. The fortress was equipped with cannons, military barracks, wells and an arsenal that held sufficient ammunition and supplies to endure a siege lasting up to two years. The fortress covers an area of 10,000 square metres, in the shape of a trapezoid. The four corners of the fortress protrude to form bulwarks.

Opening hours: 
Fortress and garden: 7 a.m. - 7 p.m.
Macao Museum: 10 a.m. - 6 p.m., last admission until 5:30 p.m. (Closed on Mondays, open on public holidays)

source http://en.macaotourism.gov.mo/sightseeing/sightseeing_detail.php?c=10&id=129#.WDgKFfmLTcc