The Eesti Meremuuseum (Estonian Maritime Museum) is partly located in Fat Margaret, a 16th century artillery tower, at the northern end of the old town, facing the harbour.
In the museum tower they show drawings of Tallinn back to 17th century, photos and documents of World War I and the Independence War 1918 - 1920, and objects of ship building, life on board and history of the area.
When we visited Tallinn on a sunny day in August 2015,
the weather was fine and we very much enjoyed the relaxing atmosphere of the
harbour and the old town. From the roof terrace cafe of Fat Margaret we had
a fine view over town and harbour.
It is a small museum but very much worth visiting when you are in town.
There is more information on the homepage of the Estonian Maritime Museum.
In the early drawings
of the town the tower is already prominently shown.
I include some pictures of a topsail-schooner in 1 : 10 scale that served as a training model and of a model of an icebreaker tug that served as gunboat in the Estonian Independence War.
If you click on a photo you will get that photo in high resolution.