A manhole rehabilitation system where in one example an existing cross-pipe is exposed and a manhole base and riser are cast around and above the existing cross pipe to form a manhole. In one example an FRP base liner and FRP riser liner are placed before casting in place. In one example casting is made of an aggregate. In one example, a collar and manhole cap rest upon the casting, and are supported thereby such that the liner need not be structural. In one example an existing pipe or manhole forms the outer surface of the casting. In one example shoring is placed and used as the outer surface of the casting.