Serqet's Altar
Essentially a radscorpion lair in Aaru, but with a very high level kingbeast.
If you do wander by while underlevelled, note that the Nefertiti statues everywhere are climbable.
When you're ready, use fire, and arrows, and fire arrows to slay the kingbeast, completing the location.
Note that there is also a treasure here, but nothing special.
This is also one of the five Sting in the Tale Achievement locations.