Rosenborg Castle

Rosenborg is the most enchanting royal building in Copenhagen and the best single introduction to the Danish monarchy. King Christian IV, the great builder-king of the early seventeenth century, raised it as a summer house outside the city walls and kept enlarging it until it became a small castle in the Dutch Renaissance style, all red brick, sandstone trim and green copper towers, set in the royal park he laid out around it. Later kings moved their main residence elsewhere, and from the eighteenth century Rosenborg became the place where the royal family kept its treasures, which is why it feels today like a perfectly preserved royal home rather than a museum built afterwards. The visit climbs through the castle floor by floor. The ground floor holds Christian IV's own rooms, including his study and the Winter Room with its painted panels and a few clever devices the king loved, among them openings in the floor that let musicians play unseen from the room below. The middle floor shows the rooms of later kings, with tapestries, porcelain and portraits, and the top floor opens into the Long Hall, the great hall of the castle, where the coronation throne of narwhal tusk stands guarded by three life-size silver lions, beneath a stucco ceiling and walls hung with tapestries of Danish victories. Then you go down to the basement treasury, the highlight for most people, where the Danish crown jewels and regalia are displayed: the crowns of the absolute monarchs, the queen's crown, swords and sceptres, and a dazzling set of jewellery still worn by the queen on state occasions. Entry is by time-slot ticket, with slots allotted every ten minutes because the castle limits the number of guests in its small rooms. Buying online in advance lets you skip the queue at the ticket desk and costs a little less: adults pay 140 DKK online and 150 DKK at the door, students 100 DKK, and children and young people under 18 go free. The castle is open daily in summer and closed on Mondays the rest of the year. Give it an hour and a half, and the gardens as long as you like.

The man behind it is a large part of the fun. Christian IV, who reigned for sixty years from 1588, was Denmark's most famous king, a tireless builder who gave Copenhagen the Round Tower, the Stock Exchange and whole districts, a heavy drinker and lover, and a war leader who lost an eye in a naval battle. Rosenborg was his favourite home, and he died here in 1648. His rooms are full of personal touches, and the later rooms trace the change of style through the Baroque and Rococo, so the castle works as a walk through two centuries of royal taste. The Royal Danish Collection runs it, as it runs the museum at Amalienborg and the visits to Christiansborg, and the Royal Palace Pass, at 245 DKK online, covers all three within three days if you plan to see them. Copenhagen Card holders get a free ticket at the desk on the day but cannot reserve a time slot online, so they should arrive early in busy periods.

How to visit well: book the first slot of the day, when the rooms and the narrow stairs are calmest, and go up through the castle before coming down to the treasury, as the route intends. Bags must be left in lockers, and the rooms are small, so the pace is slow when the castle is busy. In the treasury, take time over the details: the crown of Christian IV, made in the 1590s with gold, pearls and enamel, is one of the great pieces of Renaissance goldsmith's work, and the crown of the absolute monarchs is still placed on the coffin at royal funerals. The Long Hall's silver lions are one of the most photographed sights in Denmark.

The King's Garden, Kongens Have, is Copenhagen's oldest royal park and a favourite spot for picnics, with avenues of trees, rose beds and a statue of Hans Christian Andersen. The barracks of the Royal Life Guards stand beside the castle, and every day the guards march from here through the streets to Amalienborg for the changing of the guard at noon, so you can follow them after your visit. Torvehallerne, the food market at Norreport, is a five-minute walk away for lunch, and the Botanical Garden and the National Gallery are just across the road.