A walk in the park, Stockholm Sweden

Not exactly in the city center, but a good option if you are nearby and want to have a calm walk or is looking for a nice area to do some exercise. Its the castle of Karlberg (Karlbergs slott) and the park located behind the castle.

The castle itself is a white building that was built 1634 and the construction has been altered after that. First it was royal owned but later in 1792 they started up the Military Academy and it still is, so a fun fact is that it's the oldest military academy in the world.

The area is guarded with gates etc but during daytime its open for visitors in the park and you can pass by in front of the castle anytime during the day or night. 

View to the castle from the park

It's a quite spacious park with good tracks for walking or running

Close to the city parts of Vasastan and Kungsholmen

The canal of Karlberg (Karlbergskanalen)