There’s a hallway from here with several nooks that hide waiting Draugr- but you can use their wake-up time to kill or mostly kill them (again) and this keeps them from being much trouble. The room immediately following has several tables with various potions scattered around- make sure you check the urns for random pocket change, too. You never know when you’re going to need just a few more septims. From here, head into a new hall but look out for the pressure plate- one of the annoying swinging spiked grates is here, and you may have to rush past it just to get by before your follower or Anska can trigger the thing to spikeslap you. Fortunately, your followers and ‘companion’ are quick enough to avoid triggering it a second time as long as you’re far enough ahead.
After this is a puzzle room- it looks like something might lie in ambush for you here, but that’s actually a lie- instead it’s a big empty room with some amusing architecture. Namely, the faces with animal images in their mouths. In addition to the eagle, whale, and snake that ought to be rather familiar by this point, there is a wolf carving as well. These are found on a number of familiar pedestals- but instead of being rotatable, they are all topped with levers. A short look around the room reveals a set of faces carved into the gingerbread near the ceiling, so make note of the order of animals and then pull the levers in that order to open up the grate covering the stairs. Which stairs? The ones in the center of the lower area of the room, of course!
Charge down these with impunity- unlike the similar spiral stair in the Bleak Falls Barrow, no skeevers lurk here to chew your ankles off and provide potions ingredients. Instead there is a door at the bottom. Use this to enter the lower part of the ruins- the Catacombs. The initial room here has a couple of tables to go over for anything interesting (not much) and a hallway- that leads to another spiral stare that again is thankfully devoid of life (or unlife) that intends to make a meal of you and/or your parts.
This stairway is curiously longer than the one between the two sections of ruins, and leads to another hall. Again, toss the place for useful things before approaching the doorway into the Draugr Tunnels. This area is strangely devoid of draugr for a place named after them, instead containing a couple of nasty traps- watch for the pressure plate, it triggers a hail of arrows, and be cautious when opening the chest unless you like fresh spear injections. A little wariness will let you do everything you want here (including emptying out that chest) without getting stuck by anything pointy, though.
After this is a semicircular room containing a single draugr and some loot- and a floating Soul Gem. You can leave this alone if you like, but the only real punishment for taking it is that the standing coffins in the ‘arch’ of the room open up and release a pair of draugr- since these are regular draugr, it’s not much to worry about and besides, they tend to have money and decently expensive weapons on them. Is this supposed to be punishment for swiping the Gem? It’s not much of one, if at all.