Christiansborg Palace

This is the only building in the world that houses all three branches of a nation's government under one roof — the Danish Parliament, the Prime Minister's Office, and the Supreme Court all operate from Christiansborg. The palace sits on the tiny island of Slotsholmen, where Bishop Absalon built Copenhagen's first castle in 1167. That original fortress was eventually replaced, then replaced again, and the current building is essentially version five of a structure that has occupied this island for over 850 years. Beneath the modern palace, you can still walk through the excavated ruins of Absalon's castle — limestone walls from 1167 sitting under a building completed in 1928.

The first Christiansborg was commissioned by Christian VI in 1733 and designed as the largest palace in Northern Europe. It burned in 1794. The second Christiansborg, completed in 1828, burned again in 1884. At that point, the Danes essentially shrugged and built a third one, this time with better fire safety. The current palace was designed by Thorvald Jørgensen in granite sourced from across Denmark, with every region contributing stone so the building would literally be made of the entire country.

The Royal Reception Rooms upstairs contain seventeen tapestries by Bjørn Nørgaard depicting one thousand years of Danish history in a style that is aggressively modern and deliberately provocative. Queen Margrethe II commissioned them in 2000, and they caused considerable controversy when unveiled — which was, by all accounts, exactly the queen's intention. The Great Hall ceiling is covered in a massive painting by Kræsten Iversen, and the throne room still hosts formal receptions.

The tower, at 106 metres, is the tallest in Copenhagen — taller than City Hall, taller than any church spire. Since 2014, visitors can climb it for free, making it the best free viewpoint in the city.