What are the most worthwhile things to do in Copenhagen on a first visit?

Rosenborg was raised by Christian IV between 1606 and 1634 as a summer residence outside the city ramparts, and it still holds the Danish crown regalia in its basement treasury. The same king is responsible for the Round Tower, built between 1637 and 1642 as a university observatory, which is why its interior is a spiral ramp rather than a stair — it had to carry instruments and carriages upward.

The National Museum of Denmark holds the objects that anchor the country's prehistory, including the Trundholm sun chariot and the oak-coffin burials of the Bronze Age. Christiansborg Palace is the working seat of the Folketing, the Danish parliament, as well as the Supreme Court and parts of the royal household — one building carrying three branches of the state, which is unusual anywhere in Europe.

For the heritage layer, you leave the city. Roskilde Cathedral, inscribed in 1995, is the burial church of the Danish monarchs and sits about 20 miles west. North of the city, the Par force hunting landscape in North Zealand was inscribed in 2015 — a forest ruled into straight hunting rides and star-shaped junctions, laid out as a baroque geometry imposed on woodland rather than as a building.

The Round Tower's ramp climbs in a continuous curve with no steps to break the rhythm, so the ascent feels less like a staircase than a slow walk up the inside of a cylinder, and the city appears all at once at the top rather than in slices through windows.

The driverless Metro runs on the M1 to M4 lines around the clock, which makes the central collections trivially easy to chain together late into the evening — but it reaches only the city's own edges. Roskilde Cathedral, 20 miles west, and the Par force forests to the north both need mainline rail or regional services, so the two UNESCO components of this list belong to a different travel plan than the three palace-and-museum visits.

• Royal interiors — Rosenborg for the regalia and Christian IV's 1606–1634 fabric; Christiansborg for the parliamentary and judicial rooms in one visit.
• Deep history — The National Museum for the sun chariot and the Bronze Age burials, which are the objects Danish archaeology is built on.
• One day out — Roskilde's 1995-inscribed cathedral for the royal tombs, or the 2015-inscribed hunting forests to the north for the baroque ride system.

Christiansborg is in active use by the Folketing, the Supreme Court and the royal household, so individual rooms close without notice when the state needs them, and that is not seasonal — it follows the parliamentary and court calendar. The two UNESCO properties are outside the city, which means the published Metro convenience does not apply to them, and in the dark months the usable daylight at the far end of a 20-mile train trip is short.

Pair this with the Copenhagen food question in this group for where to eat between museum visits, and with the Copenhagen when-to-visit answer for the daylight figures that decide how much you can fit in.