- Visit Akershus Fortress, which has been in continuous use for more than 700 years - This incredible structure has never been captured by force by any foreign military in history - See the Akershus Castle church, the Royal Mausoleum, models of the castle, reception rooms, and more - Step into the Old Royal Palace, which offers breathtaking views of the Oslo fjord - Throughout the walk around the city center, many highlights and historical buildings can be seen