As its name suggests, the museum is located in the town of Marathon and it has been open for the public for more than 30 years. The exhibits to be seen there are objects from local sites, yet some of them are copies only and so to see the originals, you need to go to the National Archaeological Museum in Athens. The museum collection is divided into several rooms depending on the era - from prehistoric times till the first two centuries of the Christian era. Among the exhibits, you can admire ancient military equipment, ceramics, funeral objects, statues and figures, glass and porcelain objects, and more. 

The museum is open daily except Mondays and holidays. You can access it for a fee (for children and students the museum is for free).