The history of the Muiderslot (Castle Muiden, where muiden means rivermouth) begins with Count Floris V who built a stone castle at the mouth of the river back in 1280, when he gained command over an area that used to be part of the Sea of Utrecht. The River Vecht was the trade route to Utrecht, one of the most important trade towns of that age. The castle was used to enforce a toll on the traders. It is a relatively small castle, measuring 32 by 35 metres with brick walls well over 1.5 metres thick. A large moat surrounded the castle.
A hundred years later, in 1370, the castle was rebuilt on the same spot based on the same plan, by Albrecht, Duke of Bavaria, who at that time was also the Count of Holland and Zeeland.
The next famous owner of the castle shows up in the 16th century, when P.C. Hooft (1581-1647), a famous author, poet and historian took over sheriff and bailiff duties for the area (Het Gooiland). For 39 years he spent his summers in the castle and invited friends, scholars, poets and painters such as Vondel, Huygens, Bredero and Maria Tesselschade Visscher, over for visits. This group became known as the Muiderkring. He also extended the garden and the plum orchard, while at the same time an outer earthworks defense system was put into place.
At the end of the 18th century, the castle was first used as a prison, then abandoned and became derelict. Further neglect caused it to be offered for sale in 1825, with the purpose of it being demolished. Only intervention by King William I prevented this. Another 70 years went by until enough money was gathered to restore the castle in its former glory.
The Muiderslot is currently a national museum (Rijksmuseum). The insides of the castle, its rooms and kitchens, have been restored to look like they did in the 17th century and several of the rooms now house a good collection of arms and armour.