4 places
Halloween and Christmas are perfect for discovering Tivoli. Note that it's closed during the winter except for Halloween and Christmas.
The tower marks the geographical center of the city from which all map points were measured in years gone by. It's a great way to view the city of Copenhagen, assuming it isn't raining.
This Opera House is a must-see. If you get a chance to see a show there, you should take it.
No admission is charged for the permanent part of the exhibition, but sometimes you have to pay for a temporary exhibition.