The Caldecott Tunnel is a four-lane high way cutting through the Berkeley Hills that connects Oakland and Orinda, two cities in California. It also serves as an entrance to Camp Jupiter.
Jason Grace saw the tunnel as he, Piper McLean, and Leo Valdez were flying in a helicopter from Mount Diablo, following the rescue of Piper's father. Jason felt somehow connected to tunnel, but before he could think any more of it the helicopter had flown past.
On the highway, Percy Jackson stumbled upon a woman named June, who asked him to carry her across to Camp Jupiter. He agreed, and carried her there, crossing a river along the way. The Gorgons chased them, but they managed to get through the tunnel with the help of Frank Zhang and Hazel Levesque.
- It was named after Thomas E. Caldecott, a mayor of Berkeley Hills.
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