Greymoor, Black Moor, or Darkmoor is a fortified settlement located deep into the Whiterun plains of the province of Skyrim. Greymoor serves as the military bulwark of the city-state of Whiterun, but it has been used as an Estate during the time of Tiber Septim.
Greymoor is located in a strategic area, on the crossroad between Falkreath Hold in the south, the region of Hjaalmarch to the north, and the rest of Whiterun Hold to the east. The layout of Greymoor is the standard version that is seen throughout the other strongholds of Skyrim. The Courtyard is rather open, with several encampments for the residents of Fort Greymoor. Underneath Castle Greymoor, there is a hidden entrance leading into the inner keep and coming from a small river descending from the Western Hills. Fort Greymoor is also very isolated from the rest of Skyrim, the nearest settlement to the town is Whiterun and Sungard. The scope of Greymoor is rather small, but when Sven Advenson was named the Count, the area around the township was named the County of Darkmoor. The scope of the County is unknown, but it may have bordered the Kingdom of Whiterun considered their proximity.
The township of Darkmoor was given to Sven Advensen after his services in the Tiber Wars, he was named the Count of Darkmoor because of this reward. Around the same time, Tiber Septim had fought against the Dark Elves of Morrowind and had defeated the Armies of Mournhold, defeating the King and Queen of Mournhold. Amidst the battle, Symmachus, a Dark Elven General of the Septim Army had discovered the youngest daughter of the King of Mournhold whose name was Barenziah. Symmachus did not want to kill the young child, and so he left the child in the care of Count Sven in his Castle in Darkmoor. Sven and his wife, Inga had treated Barenziah as their daughter, and so she was raised as a noble, but she yearned to explore the outside world. In Darkmoor, Barenziah befriended Straw, a donkey-brained stable boy out of pity. Straw told Barenziah a seditious conspiracy against her, saying that Sven was going to sell her as a concubine to the King of Rihad. Because of this Barenziah and Straw escaped Darkmoor to the city of Whiterun.
During the Imperial Simulacrum from 3E 389 to 3E 399, Emperor Uriel Septim VII was imprisoned along with Talin Warhaft in the Deadlands by Jagar Tharn. Tharn planned for months to capture the throne, and he was able to achieve so in the span of ten years. Tharn had a powerful weapon called the Staff of Chaos, and he split it into nine pieces and scattered them across Tamriel, the staff was the only thing keeping Uriel Septim and Warhaft in Oblivion. A warrior escaped his clutches and traveled all corners of Tamriel to retrieve the missing pieces. The hero was known as the Eternal Champion, and he assembled the staff and defeated Jagar Tharn at the Imperial Palace. The Eternal Champion had at one point visited the town of Black Moor in their quest to recover the pieces.
During the Skyrim Civil War in 4E 201, the fortress of Greymoor was occupied by the Bandits of the region, losing the significance it once had before the war. During the Civil War, the city of Whiterun was allied with the Imperial Legion of West Skyrim. Although, the Jarl of Whiterun, Balgruuf the Greater was basically neutral in the war and was more focused on his domain than the war, this had left Balgruuf in a difficult position where he had to choose in this conflict. At some point in the war, the Battle for Whiterun had commenced, and the victor is unknown. Whoever won the battle, had possession of Fort Greymoor, even though the Leader of the militia operated out of Dragonsreach, the fortress of Greymoor became the center of Whiterun's military force throughout the war.