Mandagapattu Cave Temple is a Hindu temple situated in the village of Mandagapattu in the Viluppuram district of Tamil Nadu.

This shrine, called the Trimurti Temple, is generally considered as the first of the Pallava cave-temples and was commissioned by Mahendra I in the early 7th century on a 100ft hillock. The Pallava temples along with a similar group by the Chalukyas of Badami represent the earliest Hindu stone temples in southern India. The temples were a significant architectural innovation as they marked the transition from wooden structures to stone. An inscription on the temple calls it the Laksitayatna and dedicates it to Brahma, Isvara, and Vishnu.

Mahendravarman showed leanings towards Jainism before he gravitated towards Hinduism — which is probably why one finds Jain settlements near his cave temples.

Steps at the end of a wide stone courtyard, lead up to an uncovered porch before a simple rectangular mandapa with four massive equidistant pillars.

The pillars of the mandapa facade have square bases, octagonal central sections and square capitals with curved corbels. Inside, another row of similar pillars divides the mandapa into three aisles. The aisles lead to the Trimurti shrines, deep plain niches cut into the rear wall.

Source:

http://hill-temples.blogspot.in/2011/03/mandagapattu.html

http://www.harekrsna.com/sun/features/10-09/features1525.htm