Think there are 3 or 4 gates you can open depending on how you come in, can't remember exactly.

Other then the one above's solution you need to look up and see if there is a way to go high to find a lever to open the gates.

Windows 7 pro 64 bit
EVGA X58 motherboard
6GB of OCZ DDR3 memory
watercoooled i7 920 @ 3.8GHz (4+4 cores)
EVGA (Nvidia) GTX 275 graphics
Creative X-fi elite pro sound card.