Not far from Bikaner is a small town called Deshnoke which to all intense and purpose would not merit a second look except if you gave heard of Kari Mata who was a Hindu Goddess and has a temple there which is also known as the "Temple of the Rats" and for good reason as they are worshipped and run riot in the temple
There is no charge for going in although there is a small 50 INR Fee for taking pictures which you obviously pay. How else are you going to prove you were crazy enough to travel half way around the world to share a temple with a load of rats.
There is a story that there is a white rat somewhere in the temple and it is good luck to find it!! Personally I think the only way there is a white rat is if one fell in the trays of milk they set out for them.