500 baht for adults and 250 baht for children. There is a two price system and Thai people only pay 350 Baht/175 Baht. You can get this price if you have a work permit.
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The Ancient Siam, or Muang Boran in Thai, is like an open book of history and an open door to the real Thailand. Here you will find numerous reproductions of palace halls, temples, stupas, stone sanctuaries and traditional houses. You can also visit several reconstructed historical buildings, authenticated communities with their inhabitants doing their daily chores and sample villages from all regions of the country.
If you want to take your car in then it will cost you 300 baht. If you don't have your own car, you can rent bicycles for free, golf carts for 200-500 baht or join a tram tour for free. Thai people have to pay extra for the tram tour. Some people walk around the park but it is really too big and too hot to go on foot. There are places to buy drinks around the park. A good place to eat are the restaurants at the floating market area.
Read more: http://www.paknam.com/tourist-attractions/ancient-siam.html#ixzz2pirxdybw