sentences:  Ouderkerk aan den IJssel, together with Lageweg and IJssellaan, was a separate municipality until 1 January 1985 when the municipalities in the Krimpenerwaard were reorganized and it was merged with Gouderak to form the municipality Ouderkerk.Of these, Ouderkerk aan den IJssel is the largest population centre and the location of the town hall.The town is named for its "old church", which was a prominent landmark for centuries on the horizon for ships travelling along the IJssel river.