The dig site is located on the planet Therum in the Knossos system of Artemis tau as there is no icon on the map once u reach the system its self
Hardest part of this mission is out side the ruins it self not only do you fight an armature but the most anoying enemy in mass effect 1 the geth stalkers. Best tip for this fight on insanity is run up and engage the fight then pull back as far as u can to the ridge and snipe them as to get an angle on you they will jump up on the catwalk to the right. You can deal with all the jumpy buggers much easyer.
Inside the dig site its self the code for the laser is A X B Y X (it is different to the xbox 360 versions code)