Akershus Fortress

This fortress has been besieged at least six times and never once been taken. The Swedes tried in 1308, 1449, 1502, 1523, and 1567. Charles XII of Sweden had another go in 1716. Every single attempt failed. Akershus has stood on this headland overlooking the Oslofjord since King Haakon V ordered its construction around 1299, and for over seven hundred years it has been the most stubborn piece of real estate in Scandinavia.

The castle started as a medieval stronghold and was converted into a Renaissance palace in the 1600s. Inside the Royal Mausoleum lie the remains of Norwegian kings and queens stretching back centuries — King Haakon VII, King Olav V, and even the medieval King Haakon V himself. But Akershus has a much darker side. During the Nazi occupation, the fortress became a prison and execution site. Forty-two Norwegian resistance fighters were shot here. After liberation, the fortress hosted a different kind of justice: eight convicted traitors were executed within its walls, including Vidkun Quisling — the man whose surname became a dictionary word for "traitor" in multiple languages.

The ghost stories are inevitable. A guard dog named Malcanisen was allegedly buried alive at the main gate to protect the fortress — legend says anyone bitten by its ghost will die within three months. Visitors report battle screams near the drawbridge and an apparition in the Virgin Tower. And if the name Akershus looks familiar from a Disney movie, that's because it was the primary inspiration for Arendelle Castle in Frozen. The production team visited Norway to research the film, and the green roofs and stone walls are unmistakable.

Seven centuries of sieges, executions, ghosts, and a Disney adaptation. Not bad for a castle that started as a Norwegian king's insurance policy against the Swedes.