The heart of Copenhagen is ringed by a series of lakes to the northwest and by the inner harbour to the southeast. It is characterised by narrow and predominantly pedestrian streets lined with gabled houses, enticing shops and cafés. The huge Rådhuspladsen (Town Hall Square) lies at the western end of the central area. From here, a series of pedestrianised streets (Strøget) extend as far as Kongens Nytorv (King's New Square). The castles of Rosenborg and Amalienborg and the seaman's district of Nyboder are to be found in the area to the north and east of Kongens Nytorv. Slotsholmen Island, the site of Absalon's original bastion, lies to the southwest. The inner harbour separates the main part of the city from Christianshavn. This island was first developed in the 17th century, when Christian IV offered tax incentives to encourage merchants, shipbuilders and tradesmen to settle there.

In the 20th century, Denmark has achieved international renown for its contemporary design. Arne Jakobsen's furniture graces cool bars and cafés worldwide (not least in Copenhagen). In the city, the architectural heritage of Christian IV is supplemented by daring 20th-century buildings, including the glittering waterfront extension to the Royal Library, known as the ‘Black Diamond'.

In the streets to the north of Strøget is the Rundetårn, the oldest observatory in Europe. Built by Christian IV, the building forms part of a 17th-century scholastic complex that also included a university library (now an exhibition hall) and student church. A 209m (686ft) spiral ramp leads to the top of the tower, from where there is a good view over the old parts of the city.

Tivoli is one of the most famous European amusement parks, Tivoli is a bizarre mixture of the natural and the artificial. Designed by Georg Carstensen, in the 1840s, as a pleasure ground for the masses, there are two theatres, an open-air stage and a museum in addition to the rides. The Tivoli Boys Guard parade through the gardens at 1730 and 1930 on weekends and public holidays, with a full orchestra, stagecoach and horses. Crowded, pricey and unbelievably kitsch, Tivoli remains strangely appealing, particularly at night when the trees are illuminated with lanterns. There are numerous concerts and special events held here from April to September, as well as a Christmas market in December.

Den Lille Havfrue (The Little Mermaid) has become a global symbol of Copenhagen. Erected in 1913, the statue commemorates the Hans Christian Andersen heroine and, despite being decapitated a few times, she remains perennially popular with visitors. The pleasant Langelinie path leads to the spot in the northeast of the city where the mermaid stares wistfully out to sea. Nyhavn (New Harbour) is an inlet off the Inderhavnen, towards Kongens Nytorv (King's New Square). Until recently, brothels and bars serving the visiting sailors dominated this seedy area. Now the multicoloured, 17th-century, gabled buildings accommodate bustling restaurants and pavement cafés serving traditional Danish food beside a pedestrian thoroughfare and the masts of traditional yachts. Hans Christian Andersen lived at three different houses here.