First, you'll have to have access to Happiness Island. Once you're able to go there
legally, find the Helicopter Tours (which is directly east of Happiness Island) and
steal a helicopter. Fly to Happiness Island and over the Statue of Liberty, then 
jump out of the helicopter at the statue's feet. You should land on the topmost tier
of the statue, which is basically a square platform with a door in the center of each
side. Run around the platform until you see a door with a plaque on either side of it
that reads, "No Hidden Content Here." It may seem like you cannot go through the door,
but you can-- it doesn't open, you simply walk THROUGH the door. Inside, you'll find 
an empty room with a tall ladder. Climb it, and when you reach the top, look up; there
is a gigantic beating heart, held in place by chains.