Snow Veil Sanctum is a dungeon in The Elder Scrolls V: Skyrim
Now you need to get to the Snow Veil Sanctum. This is very easy to by Fast Traveling to Windhelm then heading to the North. When you make it there, you will talk with Mercer Frey. He will explain that Karliah is inside and likely ready for him. Head over into the Sanctum and let Mercer unlock the door to the interior.
Head down the stairs and through the first room. Be ready for any number of Draugr that tend to inhabit these areas. After you go down the stairs and through the second room just continue on. In the second room, there is pull chain on the Northern wall. Use to it access a small alcove in the Southern wall with some potions inside it. The fourth room has a trap you need to trigger to advance.
Move over to the pull chain that Mercer indicates. Be sure you are between the wall trap and the chain, against the wall. This will ensure the trap will not hurt you. Head down the stairs after you.
In the next room you will find a Draugr Deathlord. There is a second one in the left wall. Be careful as you move through the corridor which has a number of bear traps scattered about it. Continue around the next corner and toward the next stairs going down. A Draugr will attack as you start toward the stairs from the bottom of them. Turn the corner to the right and another 2 Draugr Deathlords. After them is a pair of normal Draugr and another Deathlord.
Head around the corner, turning to the South. Be careful because there is a Tripwire that activates a flame pot dropping onto an oil slick. As you go South you will encounter another pair of Draugr. Take them out and then head to the Southern door. Just to the left of it, in an alcove before the door, you will find the chain to activate to raise the door. Head down the stairs.
The next room has bone chimes hanging from the ceiling. You can easily walk through them and get to the door. On the right-hand side of it you will find the chain needed to raise it up. Do so and head through it.
Go down the stairs into the next room. You will encounter another pair of Draugr Deathlords and a regular Scourge. There are a number more Draugr in this large room that you will need to deal with.
Head south in this room. You will find some wooden stairs. Take them up then turn to the South, follow it around to the North. Take this to the upper balcony. Sitting on the balcony you will find your larceny target: Model Ship
After the fighting, head over to the West. Go up the stairs there. Take them to the South and head through the corridor you find in front of you. There is a single Skeever to deal with in this hall.
Do so and then head through the caged walkway. Just go forward to reach the door leading to the next part of the dungeon.
In the next part, head down the stairs ahead of you. This will lead you right to a trio of Draugr Deathlord that is patrolling the area. Defeat them. Head to the door to the East. Use the pull chain nearby to open the door to the East. This will cause the urns to fall over.