Viruddhachalam (also known as Virudhachalam / Vridhachalam ) is a railway town and taluk headquarters in Cuddalore district in the Indian state of Tamil Nadu. The ancient name of this town is Thirumudhukundram.
The name Vriddhachalam is obtained from two Sanskrit words - vriddham which means "old" and achalam which means "mountain". Similarly it has a name as Pazhamalai, pure tamil.
Source : Wikipedia