Guruvayoor temple is one of the best temples in India, not just because of the sheer magnitude of devotees visiting the temple daily but because of the history of the temple. With records dating back to 5000 years ago, this is considered to be one of the oldest temples in India.
Lord Vishnu in the form of Krishna is the main deity in this temple. The temple tank(pond) on the northern side of the temple is called Rudratheertham. The legend say that for thousands of years, Lord Shiva and his family worshipped Lord Vishnu on the southern bank of this pond, the current location of the temple.
Strict dress code exists for people who wish to enter the Guruvayoor temple. Men are to wear mundu around their waist, without any dress covering their chest. Women are allowed to wear sari and girls are to wear long skirt and blouses. Presently the dress code for women have been relaxed with shalwar kameez(churidar pyjamas) being allowed.
There are also elephants inside the temple. You have to visit the temple at least once to understand the magnitude.