Hjerim

The house is available for 12,000. Purchasing all upgrades costs an additional 9,000. Completing Rescue From Fort Neugrad or the full Civil War questline are necessary to purchase this house. Upon the Dragonborn becoming Thane of Eastmarch, Calder is pronounced Housecarl to the Dragonborn and lodges at Hjerim.

Interactions
A part of the quest Blood on the Ice takes place here, although it is not required to have completed the quest before buying the house. However, in order to purchase the upgrades for the house, the quest must be completed. The quest is automatically gained when entering the house for the first time, if not previously completed. When completing the quest, talking to the Steward allows the Dragonborn to buy upgrades for Hjerim.

Advantages and amenities
Hjerim is the largest of all purchasable houses in Skyrim. Hjerim has two floors, a secret chamber, and the most storage space of all the houses. Hjerim also has a useful armory with mannequins, display cases, shelves, and weapon and shield racks. Hjerim has a secret chamber behind a first-floor wardrobe where the Butcher kept the parts of his victims so that he could reanimate his sister. After the purchasing the cleanup package, the mess goes away, but the secret room stays, and is transformed into an Alchemy /Enchanting workshop.

Item Displays

 * 7 Weapon Wall Plaques
 * 2 Weapon & Shield Wall Plaques
 * 3 Sword Display Cases
 * 1 Weapon Rack
 * 3 Mannequins
 * 4 Dagger Display Cases
 * 12 Book Shelves
 * See Windhelm Home Decorating Guide for more detailed descriptions.

Trivia

 * Although the Windhelm Home Decorating Guide lists a Guest Room, it cannot be purchased; it is automatically installed.
 * Purchasing the Clean-up upgrade is not necessary, but it will become unavailable after purchasing the Living Room upgrade.
 * If Falkreath was given to the Stormcloaks in Season Unending before you received the Rescue From Fort Neugrad quest in the Stormcloaks Civil War quest-line, OR if you completed the Civil War questline for the Legion, then you must complete Blood on the Ice in order to purchase the House.

Bugs

 * Do not place items in any of the inital containers if you intend to purchase the Clean-up upgrade. As part of the upgrade, the old containers will be removed from the house, along with all the items inside.
 * Sometimes the weapon racks, wall mounts, display cases, and mannequins will not work properly.
 * All aspects of the Blood on the Ice quest must be completed before acquiring Hjerim, as the house appears to be quest sensitive. A common mistake is not investigating all the areas of the house, in the first part of Blood on the Ice. This cannot be done once the house has become available for purchase, as new furnishings take the place of investigation items. If these are left undone, they may result in broken container issues, as noted above.
 * Occasionally, if you begin the Blood on the Ice quest and and complete the siege on Windhelm, Jorlief may repeatedly tell you to examine the crime scene again and again, even though the body and blood stains have been removed. This, rendering the quest uncompletalbe, makes it impossible to purchase upgrades for the house.
 * If you place the Staff of Magnus on the weapons rack, the position of the staff will slowly migrate downwards, in short and sporadic intervals, through the floor and into the first floor. Also if you place the staff in the weapons case immediately across from the stairs it will hover in the air. (This may also be true with Sanguine Rose, the Skull of Corruption, and the Staff of Zombies.)
 * In some instances, even after purchasing the "Clean Up" upgrade, the blood will still be present inside the house and the secret room will be as it was. However, weapon plaques will still be added and the bookshelf in the sacrificial altar area will be glitched.
 * Purchasing the living room upgrade before the "Clean up the Murders" upgrade will remove the option to clean up the mess, resulting in the same issue above.
 * One method of fixing the two above issues is to open the console, click on an item that should have been removed and type markfordelete. Do this for each object that should have been deleted and reload the area. Be sure to save, beforehand. Note that trying to remove the bloodstains on the floor using this method will remove the floor, leaving an opening to nothing.
 * There's also a method to remove the blood stains but it requires care (try at your own risk). Create a New Save file and open the console, click on the blood stains (or any object that has them) and type markfordelete then do a quicksave and quickload, as expected both the floor and objects will have disappeared, just load the save file that was created first and everything will be back but without the blood (not guaranteed to always work). You can also use the autosave from entering Hjerim as your starting point.
 * On occasion, the speech options for buying upgrades will not go away. If chosen again, the appropriate coin will be lost, without changing anything.
 * Two of the master bedroom dagger racks may be unusable, after storing daggers in them. More daggers may be added, causing clip issues with the old ones, though none may be removed. The other dagger racks are unaffected, as are all other displays. **It is possible to remove the daggers by using the 'tcl' (no clipping) console command and moving really close to the rack.
 * Placing the Ghostblade on any of the plaques in the house makes it disappear, indefinitely.
 * After buying the house upgrades, there may be an empty room just in front the master bedroom's doors. This room will be filled with furniture, the moment Thane of Windhelm is achieved. The Housecarl will live here. Therefore, if anything is left within this room, before the title of Thane has been bestowed, it may be stuck under or behind the new furniture.
 * After storing more that one piece of armor of one type on the mannequin near the stairs, it, after leaving the house and re-entering, generates one of those helmets, which may be taken away and sold eventually. This will not break the generating bug.
 * Sometimes, giving a mannequin Wolf Armor will make parts of the mannequin go invisible. This will not destroy the items.
 * There is some chance were any armor that is put on a mannequin will make the mannequin invisible.
 * It is possible to continuously purchase the Clean-up upgrade.
 * One of the dagger displays in the player's room is bugged (the one on top). Any dagger the player puts in it will disappear, though the image of the dagger will still be visible it is impossible to retrieve it. You may stack daggers in the display, but none will be retrievable.
 * The chest at the base of the bed may not appear. The cause is unconfirmed, but is most likely from buying the house for less than the regular price.
 * Sometimes the helmet placed on a mannequin is invisible, however the helmet is not lost and can be retrieved.
 * Sometimes the Master Bedroom may become bugged, whereby the player cannot enter, as if there is an invisible force-field in the bedroom doorway. The result being that everything stored inside the master bedroom will from then on be unavailable. Current cause and/or solution for this bug is unknown. One cause seems to be the very large hit zone of some two handed weapons placed on the weapon racks on the right side of the door. Removing the weapon from the rack resolves the issue.
 * If you do not start the Blood on the Ice quest before re-taking Windhelm for the Empire, you can be stuck in an endless loop with Jorleif that Hjerim needs to be cleaned up before you can purchase the house. On the PS3 this glitch can occur if you have completed the Stormcloak quest-line, often accompanied by an inability to start Blood on the Ice at all.
 * Equipping items directly in the mannequin menu will temporarily render the properties (i.e. improving & enchanting) of the items disappear. Unequipping and then re-equipping again fixes this.
 * If you start Blood on the Ice, not by way of purchasing Hjerim from the Jarl's steward, but by one of two other ways of initiating the quest, a problem arises after finishing the quest. When you finally buy all the upgrades to Hjerim, the real murderer (not Wuunferth) will be residing there. He will attack you each time you are in your house, and cannot be killed.
 * Sometimes the wall racks, weapon racks, and display cases will not work properly.