Lost Ruins is a course featured in Ridge Racer 7 and Ridge Racer Slipstream, located in the southern part of Ridge State, running through a derelict ancient temple.

The course is considerably tight but not as undulating as Mist Falls, although there's a drop that may send a car to a short time of air and a small crest that may does the same to a car. Three hairpins are present which may give players some chance to fill up their nitrous booster(s).