Skyrim Secondaries- Forbidden Legends: First Treasure, Then to Ivarstead

Once you've downed the Gauldurson, loot him immediately for three points of interest: the Gauldur Blackblade, the weapon he was using to steal your health; the Gauldur Amulet Fragment, which is an amulet itself and grants +30 Health to the wearer; and the Writ of Sealing, an imprecation against Mikrul himself.  Then scour the tomb for valuables (mostly in the possession of the various Draugr Thralls).  You will find a pair of porticullis locked by the Ivory Dragon Claw at the back of the tomb as well.  Open the left one first and take the coin purse from behind it, then breach the other to enter the treasure room of the dungeon.

In addition to the weapons and potions here, you'll find (likely by sound before by sight) a Word Wall, containing a word from the Frost Breath Thu'um.  This will let you belch a stream of icy cold in a fashion not unlike the annoying Blood Dragons that keep assaulting you outdoors (though less effectively so long as you're only using a single word of it).

Head through the back door to enter a narrow tunnel which leads you back to the burial chambers, right near where Daynas' corpse lies.  From here it's a short jog back out of the dungeon.

The next place to go in your tour of the betrayers' crypts is Geirmund's Hall, to the East of Ivarstead.

If you've been to Ivarstead for the sake of the main questline, this is easily reached via fast travel- if not, your quickest way is to take the road East of Whiterun that leads North around the Throat of the World mountain.  Those who are interested in avoiding falls should take the more level path, which involves a larger number of encounters, a more roundabout method of arrival, and much less slopes.  Those who want to save time should keep an eye out for the mountain path located just before the road passes by the Stormcloak camp- while the route is a touch hard to decipher and the slopes are steep, there is a virtual certainty that you'll only see goats on the path and it takes less than half the time to travel even discounting the lack of bandits and wolves.  If you want to know more about these routes, check with the main questline articles.