Louisiana museum by the sea, and the trains to Sweden

The Louisiana Museum of Modern Art, 35 minutes north of Copenhagen by train, sits in a sculpture garden above the sound with Sweden across the water; it's the best half-day trip from the city. Kronborg, Hamlet's castle, is a few stops further at Helsingør, where a 20-minute ferry crosses to Helsingborg in Sweden. The Øresund bridge train reaches Malmö in half an hour. Roskilde's Viking Ship Museum and cathedral are the other direction.