sentences:  In the year 1631, Częstochowa had 399 houses, but at the same time, several residents died in a plague, after which 78 houses were abandoned.In the first half of the 17th century, kings of the House of Vasa turned the Jasna Góra Monastery into a modern Dutch-style fortress, which was one of the pockets of Polish resistance against the Swedish armies during Swedish invasion of Poland in 1655 (for more information, see Siege of Jasna Góra).The town of Częstochowa itself was almost completely destroyed by Swedish soldiers.