I would recommend parking at the indicated waypoint, across Sand Hill from the Bank of America. You will find a path that goes along Sand Hill. It is a small walk over to the cache.
You will pass by the SLAC National Laboratory on your way there, and the cache is nearby the entrance. SLAC is a national laboratory owned by the US Department of Energy and operated by Stanford University. It is a premier scientific laboratory that draws scientists from all over the world.
SLAC is home to the LCLS (Linear Coherence Light Source) and SSRL (Stanford Synchrotron Radiation Lightsource). Both of these machines are x-ray radiation sources. LCLS is a kilometer long lube that runs under highway 280. Within this tube electrons are accelerated to extremely fast speeds, near the speed of light. Near the end of the tube, the electrons are forced to wiggle back and forth to produce x-rays. SSRL also produces x-rays, but it does so by sending electrons around a circular type motion, and at each turn, the electrons emit x-rays.
Scientists from all over the world and from many fields of chemistry, biology, and physics make use of the x-rays. One of the more celebrated uses is to image the structure of proteins, which can be done with super intense x-rays.
The funny thing is that this original purpose to this laboratory was to study particle physics. In fact, SLAC has produced three Nobel prizes in this field. But it turned out that the same infrastructure required to accelerate particles so they could be smashed together could also be used to generate x-rays. So once the particle physics research dried up, they were converted the particle smashing machines to x-ray generating machines.
As a scientist, I find this story very inspiring. It makes me realize that one cannot always predict how one's discoveries will impact the world. In this case, people who are so deep into the depths of particle physics ended up building this crazy machine that years later benefits other sciences such as biology, and it has completely changed the way we do science in a total unexpected way. Yay science!