Muiden Fortress (Dutch: Muizenfort - 'fort of mice') is a Dutch fortress in Muiden. It is part of the defence line of Muiden, that is part of the Stelling van Amsterdam, the UNESCO World Heritage site that consists of a set of forts around the city of Amsterdam.
These days, the fort is used for offices as well as a small museum, the Muider Muizenfort Museum (MMM).