Groote Zeesluis Muiden

This old lock dates back to 1674. It consists of a double-turn lock and discharge-cum-discharge sluices on both sides.

After a century of unsuccessful negotiations between Holland and Utrecht, there was no agreement yet to construct a new lock at the mouth of the Vecht in Muiden. For Utrecht, the Vecht was an important connection with the Zuiderzee. The old lock at Hinderdam, about 5 kilometers inland, was built in 1437 and was under the control of Utrecht. When in 1672 Utrecht was occupied by the French army, Holland seized its opportunity and the construction of the lock in Muiden was started.

The lock had three primary tasks: a lock for shipping traffic between the Zuiderzee and Vecht, the defense of the land against the Zuiderzee and a military function. Muiden was part of the Dutch Waterline. In the case of inundations, control of the inlet of Zuiderzee water was essential. The lock also prevented water from flowing out of those upstream areas that were flooded.

The lock was finished in 1674. The complex consisted of a double retaining lock and drainage locks on both sides. The locks complex had the task of turning the water on two sides; both on the sea side at high tide and on the river side at low tide. To be sure, the lock got an extra set of storm flood doors that were closed at extremely high water. Shipping traffic was then impossible. The lock had a length of 50 meters and a width of 7.5 meters. [6] The lock complex was expanded in 1676 with a wall along the mouth of the Vecht to prevent flooding.

(en.wikipedia.org/wiki/Groote_Zeesluis)

Especially the swing bridge from 1870 is worth seeing.