Mount Fortress, built in 1617-26, occupies a hilltop to the east of the ruins of St. Paul' s. It was constructed by the Jesuits as part of a complex which also included the college and church of St. Paul' s. The canons were used only once, when the Dutch invaded Macau in 1622. This was also the first residence of the governors of Macau. Over the following decades trees grew from the platform of the fort, which was transformed into a public park where residents and visitors came to enjoy the views. The only building was an office of the Meteorological Department until 1998 when the three-level Macau Museum, focusing on the history of Macau, was built into the fortress hill.