Melacheri is a small village in Viluppuram district.  There is a small cave excavation that it is opened only for few days in a year.

This cave temple is excavated in the western face of a small granite boulder, located to the north of the village. Locally this temple is known as Maddileshvara temple. The façade faces the west and is opposite to an irrigation tank. This rock temple is hidden by a later addition of brick mandapa in front of the cave. In the center of the cave are two pillars, and two pilasters which are square throughout. This arrangement divides the cave into three partitions of equal size. The corbel above the pillars is in angular profile, not in curved or Taranga (roll) profile as seen in other Mahendra shrines.

On the back wall of the entrance hall is cut a cell, which is entered through an oblong opening. It houses a Shiva lingam, which is cylindrical in form and resting on yoni pedestal. This stone Shiva lingam is carved from the original rock, a feature not seen in any other Pallava cave of Mahendra or later time. There is a lotus carved on the ceiling just above this lingam. The north wall of the cave has a niche cut into and there stands an image of Parvati. From the style of the sculpture, this looks like a later addition. There is a bas-relief of Ganesha in the extension of the southern wall of this cave temple. This also is assigned to later times by many scholars.

Source:

http://puratattva.in/2010/11/04/melacheri-sri-sikhari-pallaveshvaram-cave-temple-30.html