Bloodlet Throne

Bloodlet Throne is located in the southernmost mountain range. It is filled with vampires, Vampire's Thralls and a fire trap just inside the entrance activated by a pressure plate. The throne room itself is guarded by a Master Vampire and several subordinate vampires, although wolves can be found here as well. At nearly any level the Master Vampire is a challenge and can easily kill a character in light or no armor.

Interactions
Going into Bloodlet Throne early is a good way to start a character because of the numerous weak enemies, locked doors and chests, and other opportunities to grind basic skills. A new character can easily reach level 10 by the time they complete the dungeon, even without actively grinding skills and making use of exploits.

Totems of Hircine
Also, at the end of the Fort a chest can be found, containing the Werewolf Totem. This is used in the quest Totems of Hircine, which is given to the player by Aela the Huntress.

Vampirism
This location is one of the easiest locations to contract vampirism due to the weakness of the vampires inside and the fact that it is close to Helgen.

Amenities

 * Alchemy Lab
 * Arcane Enchanter

Notable loot

 * A dagger with a random enchantment is always in the store room.
 * Incident at Necrom - Illusion skill book is in storeroom.
 * Silver Ore vein in tunnel behind vampire's throne.

Quests

 * Trouble in Skyrim
 * Totems of Hircine
 * Shalidor's Insights

Trivia

 * A quick way to boost Sneak skill is to get the part of the fort where a Master Vampire is sitting on a throne on the other side of a closed gate. Instead of pulling the lever, crouch and keep walking into the metal gate; no need to go slow due to the distance to the enemy; the player is not detected, yet is close enough for Sneak skill to increase. The Master Vampire's health also regenerates quickly so it is possible to grind faster by shooting him repeatedly with a bow while sneaking. If the player is detected, the vampire will not be able to attack through the closed gate with melee weapons, but bear in mind that his Vampiric Drain spell can reach through the bars.
 * Trapping the Master Vampire behind the bars and healing yourself while taking damage from his drain spell can also help level Restoration magic.
 * There is a known bug where the Master Vampire will sometimes appear on your side of a metal grate or door when he doesn't have a path to you otherwise, especially if you trap him in one of the cages that hold the wolves in the throne room.
 * Gargoyles now appear in this dungeon once Dawnguard is installed.

Bugs

 * The "activate door bar" on the opposite side of the door allows one to avoid going through the entire dungeon.