Ancient Hindu Temples in India

There was no idol worship during Vedic period. Agnihotra or Yajna were performed. In Yajna, God is worshiped by honouring fire and fire is the vehicle that takes the request to God. However, Vedas contain hymns (mantras) to worship deities who number around 33 koti including Indra, Agni, Varuna, surya, vaayu, Vishnu and Rudra (later became Shiva). Idol worship is the extension of Yagna which is allowed in Vedas. Earlier Hindus used to worship cave temples so there was no need to construct temples. The earliest example of this kind was a cave temple that was built in around 400 B.C. at Bhaje containing images of learned Parasurama with Indra and Surya.
 
Later, worship of Kubera, Rama, Kesava, Krsna, Vishnu, Mata and Shiva started. This led to image worshipping and building of temples. Hindu Temples are spread over entire Indian sub-continent. Many temples date back to thousands of years. Sri Adi Shankaracharya (8th century) - He went on to connect holy spots of India such as the 12 jyotirlingas, 18 shakti-peethas and four Vishnu-dhams to create pilgrim routes that defined India as a single land.
 
A large number of ancient temples are found in southern and Far East countries such as Cambodia, Thailand, Malaysia, Indonesia, Nepal, Sri Lanka, Bangladesh and Pakistan. It is interesting to know that Hindu temples are spread over now in over 43 countries.
 
Indian Express dated November 26, 2019 reported, A total 651 Hindu temples in India are designated as Centrally Protected Monuments under the Archaeological Survey of India (ASI). The largest number of Hindu temples under the ASI’s protection is in Karnataka, followed by Tamil Nadu, Madhya Pradesh, and Andhra Pradesh (Karnataka – 149, Tamil Nadu – 111, Madhya Pradesh – 96, Andhra Pradesh – 91, Maharashtra – 41, Kerala – 39, Rajasthan – 30, Uttar Pradesh – 24, Gujarat – 16, Odisha - 15, Bihar - 8, J & K – 8, Himachal Pradesh – 6, Chhattisgarh – 5, Uttarakhand - 5, Haryana – 2, West Bengal – 2, Delhi – 1, Goa – 1 and Jharkhand -1. (Source: Lok Sabha question)
 
Archaeological findings of temples date back to thousands of years. A few evidences of old temples are mentioned hereunder to highlight the grand heritage of oldest religion:
 
Popular Hindu Temples constructed before the birth of Buddhism & Christianity:     

1. Times of India dated October 14, 2001 reported, discovery of 7000 years old Nandeeshwara temple at Malleswaram at 17th cross which was buried underneath. A Nandi was carved out in black stone with golden eyes. Clear water was flowing from the mouth of Nandi directly on the Shivalinga.
2. Gudimallam, Srikalahasti, Chittor, Andhra Pradesh - The Shiva Temple in Gudimallam is considered to be the one of the oldest Shiva Temple in the world. It is even mentioned by the Priests there that that temple is the oldest temple in Asia. As mentioned by the priests there, the temple is 2300 years old.
3. Dwarkadhish Temple, Dwarka, Gujarat – It is also known as the Jagat Mandir and is built in a Chalukya styled architecture, dedicated to Lord Krishna. The 2200-year-old architecture, is believed to be built by Vajranabha, who constructed it over the land reclaimed from the sea by Lord Krishna.
4. Kashi Vishwanath temple, Varanasi, UP – It is believed to be built by Maharaja Vikramaditya about 2,050 years ago, but Mughal emperor Aurangzeb destroyed the temple in 1664. It is one of the 12 Jyotirlingas or temples dedicated to Lord Shiva. The main deity of Kashi Vishwanath Temple is Lord Shiva, also known as Vishwanatha or Vishweshwarar meaning 'the ruler of the universe'. The current existing Kashi Vishwanath temple has been built on an adjacent site by the Maratha ruler, Ahilya Bai Holkar of Indore in 1780.

 
Popular Hindu Temples constructed before the birth of Islam:

1. Mundeshwari Devi Temple, Bihar – It is dedicated to Lord Shiva and his consort Shakti, this temple is considered the oldest functional temple in the world. Believed to have been built in the Saka era, the Archaeological Survey of India (ASI) dates it to 108 AD.
2. Sri Venkateshwara Balaji Temple, Tirupati, Andhra Pradesh - It is the most revered and celebrated temple of Tirupati having tourists and pilgrims flooding in all year long. This is one of the holiest and the wealthiest temples in the world and millions of devotees’ flock here to pay their reverence. (3rd Century AD). Around 50,000 pilgrims visit the temple every day.
3. Badami cave temples, Karnataka - The Cave Temples of Badami consist of four separate temples, each holding intricate carvings and depictions. These carvings depict Shiva and Vishnu in various avatars in the first 3 temples, representing the Brahmanical style. (6th century AD)
4. Lingaraj Temple, Bhubaneshwar, Odisha - It is an ancient temple dedicated to Lord Shiva. The temple was built in the 7th century by the King Jajati Keshari. It is highly revered because of the fact that the Linga here, which is the phallic form of Lord Shiva, is believed to have appeared naturally. 
5. Kanchi Kailasanathar – It is a Hindu temple dedicated to Lord Shiva. The temple was built from 685-705 AD by a Rajasimha ruler of the Pallava Dynasty. It is one of the earliest structural temples and the largest one built by the Pallavas.
6. Adi Kumbeshwara Temple, Kumbakonam, Tamil Nadu - It is one of the grandest and the oldest Shiva temple in the town. The temple has a magnificent architecture with the trademark style of the Cholas. (7th Century AD)
7. Badrinath, Chamoli district, Uttarakhand - It is dedicated to Lord Vishnu is one of the four Char Dham and Chota Char Dham pilgrimage yatras. It is situated at the height of 10,279 feet, originally established by the saint, Adi Shankaracharya in 7th Century, AD. The Temple remains closed for six months from November to April each year. On the day of the closure, an Akhanda Jyoti lamp is lit to last for six months and the image of Badrinath is transferred to Narasimha temple at Jyotirmath. Badrinath reopens on Akshaya Tritiya, an auspicious day in April every year.
8. The Kamakshi Amman temple, Kanchipuram, Tamil Nadu - It was established under the auspice of the revered Indian guru Adi Shankaracharya, whose teachings are followed by the disciples of the Goddess till date. The Pallava kings who ruled the lands in that era probably built the temple, with the Chola and Vijaynagar kings. (7th Century AD). The Kamakshi Amman temple is one of the 51 Shakti Peethas.
9. Kedarnath, Rudraprayag District, Uttarakhand – It is one of the most sacred temples and part of Chhota Char Dham Yatra. It is one of the most important among the 12 Jyotirlingas in India dedicated to Lord Shiva. During the winters from November to May, the deity is shifted from Kedarnath Temple to Ukhitmath and is worshipped there. The present Kedarnath Temple is believed to be re-constructed by Adi Shankaracharya, initially built by the Pandavas thousand years ago.  

 
Popular Temples constructed prior to Islamic invasion in India:

1. Group of Monuments at Mahabalipuram, Dist. Kanchipuram Structural Temples - Among the structural temples, the Shore temple consisting of two graceful Siva temples – Kshatryasimhesvaram (east) and Rajasimhesvaram (west), built by Pallava King Rajasimha (AD 700-728).
2. Mallikarjuna Temple, Pattadkkal - This temple, called Sri Trailokeswara Maha Saila Prasada in an inscription was built around 740 A.D. by one of the Queens, Trailokyamahadevi of Vikramaditya II (733-45 A.D.).
3. Kailasha or Kailashanatha Temple – It is the largest monolithic rock-cut structure in the world located in cave 16 of Ellora Caves in Aurangabad, Maharashtra. Kailasa Temple is an engineering marvel perfect for history and architecture lovers. (8th century AD)
4. Bhoganandeeshwara Temple, Chikballapur, Karnataka - It was constructed around 806 A.D. by Rathnavalli of Bana Dynasty in the Dravidian style.
5. Sri Ranganathaswamy Temple, Srirangapatna, Karnataka – It is a beautifully carved temple complex dedicated to Lord Ranganatha who is an avatar of Lord Vishnu in Hindu religion. The idol of Lord Ranganatha is seen in a reclining posture over the Sheshanaga. An inscription in the temple premises indicates that the shrine was first sanctified around 984 AD.
6. Sri Jagannath Puri Temple, Puri, Odisha – It was built in the 11th century by King Indradyumna. This glorious temple is the abode of Lord Jagannath who is a form of Lord Vishnu. It is the most revered pilgrimage site for Hindus and is included in the pious Char Dham Yatra with Badrinath, Dwarka and Rameswaram.
7. Ambarnath Temple, Mathern, Maharashtra - It is dedicated to Lord Shiva and was built in 1060. The temple complex has a stark resemblance to the Dilwara Temples located in Mount Abu.

Dr. S. Balakrishna of NASA, USA; Dr. B. N. Narahari Achar, Department of Physics, Memphis University, USA; Dr. R. N. Iyengar, Department of Civil Engineering, Bangalore; Dr. S. Kalyanaraman, Saraswati River Research Centre, Chennai and others submitted papers on the date of Mahabharata war based on Astronomical data with the use of Planetarium software at the two-day seminar in Bangalore, India between fifth and sixth January 2003 and agreed that there does not exist any contradiction between any two descriptions of planetary configurations given in
the Mahabharata .