The Citadel in Copenhagen is right next to the Little Mermaid. Many feels that the Little Mermaid is a disappointment. However, if you make the whole area around the mermaid your destination it is a worthwhile expedition. The harbour, the Citadel and the small marine together makes up quite a nice corner of Copenhagen.
As is the case with all other green patches in Copenhagen the Citadel is a poplular place for going for a run.
Across Denmark you will find these old mills. If you go to Copenhagen only on your visit to Denmark this is probably the closest you will get to one of these remnants of the past pre-industrial rural Denmark. If you want to get even closer to these mills, even see one from the inside – visit ‘Frilandsmuseet / Open Air Museum‘ a short train ride outside Copenhagen.
Today the heart of Kastellet houses the Danish Defence Intelligence Service in its pretty buildings.
At Kastellet you are not allowed to walk on the lawns, so this is about the closest you will get.
To reach Kastellet (the Citadel) from the Little Mermaid you cross this bridge, walk past the fountain and the church.