EQ2

You can just see my assassin on the left there, this dungeon (Vasty Deep: Vestigial Cella) was part of the epic conversion questline and I remember this being quite a fight at the time.
Lotro

Elven ruin in Eregion with a bonus night time rainbow! There are ruins and abandoned buildings almost everywhere in Middle Earth – this game has so many details which really makes the place feel as though it has history.
ESO

I have been trying to use unused screenshots but I love this image so much (my current header). This is an Ayleid ruin (ancient elf) and the light is coming from scattered Welkynd Stones.
GW2
not exactly a ruin, but parts of it are neglected and it has been hidden for a long time so I think it counts. This is Tarir, the Forgotten City in the Auric Basin. The light here is so lovely.