Much of Vijayanagar is now in ruins, as when the rulers were defeated at the hands of the invaders at the battle of Talikota in the 16th century, most of the marvelous structures and edifices were systematically destroyed.
The Virupaksha or the Pampapathi temple is the main center of pilgrimage at Hampi. It is fully intact, and it incorporates some earlier structures. This temple has three towers, the eastern tower rises to a height of 160 feet and is nine tiered. It dates back to the first half of the fifteenth century and was renovated in the sixteenth century by Krishnadevaraya.
This tower has been built such that an inverted shadow of this huge tower falls on the western wall of the temple through a small hole behind the sanctum. The northern gopuram has five storeys, and the inner eastern gopuram is endowed with three storeys.
The presiding deity here is Virupaksheshwara or Pampapathi. His consort Pampa, is believed to be the daughter of Bhrama. There is an ornate shrine to Bhuvaneswari. There is a shrine to Vidyaranya, the spiritual founder of Vijayanagar in this temple. The inner prakaram consists of shrines and pillars dating back to the 12th century.
Krishnadevaraya also built a mandapam in front of the sanctum, and embellished it with Vijayanagar style bas reliefs and murals. Several of Shiva's manifestations, and the ten incarnations of Vishnu are portrayed here, as is the classic scene from Mahabharata depicting Arjuna's shooting the fish device in order to secure Draupadi's hand in marriage. There is also a mural depicting Vidyaranya the spiritual founder of Vijayanagar in procession.
In the vicinity of the Virupaksha temple are several dilapidated mandapams. In front of the temple was once an ancient shopping center lined with mandapams, the ruins of which stand today.
Festivals: The chariot festival in the month of February is the chief annual festival celebrated here. The divine marriage between Virupaksheshwara and Pampa is celebrated in the month of December.
Source : http://templenet.com/Karnataka/virup.html