Fat Margaret Tower (Paks Margareeta), Tallinn

The Fat Margaret (Estonian Paks Margareeta) is a defense tower of the Revaler city fortification in the Estonian capital Tallinn (Reval).
Source: Wikipedia

Here is also the Estonian Maritime Museum housed.
The fat Margarethe is UNESCO World Heritage.

The north end of Pikk Street is guarded by two of Tallinn's most impressive defenses: the Great Beach Gate (Suur Rannavärav) and the Big Margaret Tower (Paks Margareeta).
Not only were they built to defend the city from attack from the sea, but they also impress every visitor who arrives at the port.
Today the Dick Margarethe tower houses the Estonian Maritime Museum, which presents all the important aspects of seafaring in Estonia's history. You can see fishing equipment from the Stone Age, old diving equipment and a complete wheelhouse from a trawler from the 1950s. The extensive museum is housed on four floors.
You can climb to the roof and enjoy the postcard view of the harbor and the old town.
The origin of the name “Big Margaret” is unclear. According to some theories, it comes from the larger cannons, others point to a cook named Margarethe who once worked here.
In any case, the tower has had different functions over time. It was a powder store, an armory and also a prison.
Source: Tallinn Tourist Information