Understone Keep is a seat of the Ard in Markarth. It can be accessed through the main entrance in western Markarth. When you enter the building, you have three options: head north, head south, or continue west. Traveling north brings you to the Announcement Hall, which is unlocked during the last epilogue quest, and remains accessible after the quest is complete. If you head south, you'll reach Nchuand-Zel. After a certain point in Story Quest progression, the entrance to Nchuand-Zel becomes unlocked, connecting the building with a section of the Blackreach caverns. A copy of Legend of Arkthzand is sitting on a side table in the north side of this room. A copy of the lore book, Nords of Skyrim, is located in a pavilion along the eastern wall.
Moving west brings you to the ard's throne room, with the Mournful Throne in the middle. A book titled Politics of the Reach is on a table sitting against the southern wall. Walking up the stairs and entering the room right to the north of this chamber will bring you to the kitchen. The room west of the kitchen contains a copy of the lore book, Varieties of Faith: The Nords and a master safebox. Heading further west brings you to a planning room with a table in the center. There is a pile of coins which you can steal on the table.
South of the throne room lies a gathering place for guests, where a bard is playing. A master safebox is sitting on the floor next to a bed in the southeastern corner of the room. The hallway west of the entrance to the bard's room brings you to a large, well-decorated bedroom with a view of the river running through the ruins.
- The Despot of Markarth: Secure an alliance with the Despot of Markarth.
- Blood of the Reach: Search for the Arkthzand Keystone.
- The Study of Souls: Search for Lady Belain and the Ashen Lord in a Dwarven ruin.
- The Awakening Darkness: Learn more about the prophecy the Gray Host seeks to fulfill.
- The Dark Heart: Search for the truth about the Dark Heart.
- A Feast of Souls: Stop the vampiric assault on Markarth.
Dark Heart of Skyrim Epilogue
- The End of Eternity: Discover how to travel through the Void.
- Kingdom of Ash: Enter the Void and put a stop to the Darkstorm.
- Second Chances: Receive your accolades in Understone Keep.