The Fortress of Nerra, later called Olt's fortress, was the home of the Chieftain of Dorne and its family. From the fortress the Chieftain ruled over Dorne and kept order. The fortress was a large stone structure which stands in the harbour city of Nerra on the island of Dorne. It faced the harbour and the waters known as the Sea of Serpents that surround Dorne. A thousand years ago, when Chieftain Peregrine passed away, the Fortress became the seat of power for Annoltis and the city's name was changed to Oltan, until Dorne was rid of his tyranny partially by the actions of Rye, Sonia and Dirk of Weld.
After the death of Olt, the fortress was set on fire. and was reduced to a ruin never to be reconstructed. Instead, at one point a museum was built on the ruins, the only thing still remaining of the original fortress being a large stone maze located under the ground. Later, in the present day, the museum building was also destroyed, as a Shadow Lord spy named Barron caused it to collapse.