It is Tamil Nadu's fourth largest City after Chennai, Madurai, and Coimbatore with an estimated population of 1,067,915 (as of 2008).
It is situated in the centre of the state, on the banks of the Cauvery River. Trichy is a Municipal Corporation and the administrative headquarters of Tiruchirapalli District.
The most famous landmark of Trichy is the Rockfort temple which is perched on a huge rocky out crop. The smooth crop was first hewn by the Pallavas but it was the Nayaks of Madurai who later built the Rock fort temple. The temple is dedicated to Lord Shiva and Lord Ganesha.
Trichy city encompasses Srirangam, a Vaishnavite temple and the biggest functioning Hindu temple in the world. Trichy also contains "ThiruAnaikka" (ThiruvAnaikkaval), House of Water, one of the five main abodes ("Panchaboodha Sthalam") of Lord Shiva. Chandrasekhara Venkata Raman was born in Thiruvanaikaval and his house has been preserved as a museum.
Tiruchirapalli was originally a Chola citadel and later, during 1st millennium AD, it was occupied by other south Indian dynasties such as the Pallavas and Pandyas. The Chola's regained control over Tiruchirapalli during the 10th century. Nearby Urayur was the capital of the Early Cholas. Later, after the fall of the Chola empire, it came under the direct control of the Madurai Nayak Dynasty who paid tribute to the Vijayanagara empire. The Rock Fort temple, the most famous landmark in Tiruchirapalli, was built by the Nayaks. The Madurai Nayak rulers changed their capital from Madurai to Tiruchirapalli, and back, several times.
The city is home to Nagaraj Cholan and many historic temples, monuments, churches and mosques. Urayur, the Old Tiruchy, has over 2,500 years of known history and tradition. It was the capital of the early Chola kings. The oldest human-made dam, Kallanai, was built by Karikala Cholan across the Kaveri River about 10 miles from Urayur.
Trichy was an important town in the days of the Later Cholas and of the Nayak kings, and during the early days of the British East India Company. The conquest of Tiruchirapalli by the British East India Company marked a major step in the British conquest of India.
One famous landmark in Tiruchirapalli is the Rock Fort, a large outcrop of rock, 83 metres high. It is the only such outcrop in the otherwise-flat land of the city, and because of it Trichy is also called Rock City. On top of the rock is the Ucchi Pillayar Koil, a temple dedicated to the Hindu god Vinayaka (Ganesha), from where one can enjoy a panoramic view of Tiruchirapalli. The temple was also used as a military fort by the Nayaks for some time.
On the southern face of the rock are several beautifully-carved cave temples of the Pallava period. On the eastern side is Sri Nandrudayan Vinayakar Temple, with Ganesha as the main deity. A large-sized Ganesha and depictions of other rare deities can be seen in this temple, which hosts festivals every year during the Vinayaka Chathurthi (birthday of Ganesha). Many Carnatic musicians have given concerts in this famous shrine. Around the rock temple is a busy commercial region, specializing in textiles, known as Chatram. The Main Guard Gate is flooded on festive occasions such as Deepavali, Ramzan, Bakrid, Christmas, and Pongal.
Trichy is famous for the number of Christian churches it contains -- it is said to have the greatest number of chapels in India. The most famous are Holy Redeemer's Church (Sagayamatha Koil), Lourdes Church, and The Cathedral.Trichy also is famous for Arcot Nawab masjid (one of the oldest) , with its large water storage tank (Ahil) .
The topology of Trichy is flat. It lies at an altitude of 78 m above sea level. The river Kaveri (also called Cauvery) and the river Coleroon (also called Kollidam) flows here, the latter forms the northern boundary of the city. The river Cauvery flows along WNW-SSE direction through the city.
There are a few hills located within the city, the prominent among them are Golden Rock, Rock Fort, and the one in Thiruverumbur. There are few reserve forests along the river Cauvery, located at the west or the north-west of the city. The southern and the south-western part of the district is dotted by several hills which are thought to be an offset of the Western Ghat Mountain range—the soil here is considered to be very fertile. As two rivers flows through the city, the northern part of the city is greener than other areas of the city.