The Counts of Holland expanded their influence, and by 1165 they built a fort called Svadeburg, near present-day Zwammerdam, about 7 miles to the west of Woerden.
Conții de Olanda si-au extins influența lor, și din 1165 au construit un fort numit Svadeburg, langa prezentul Zwammerdam, la 10 kilometri vest de Woerden.