Aerial photograph of the 3. 2 km (2 mile) long linear accelerator at the Stanford Linear Accel- erator Center (SLAC), California. The end at which the electrons start their journey is in the foreground; the experimental areas where the accelerated electrons are smashed into targets, or used for further acceleration in electron-positron colliders, is beyond the freeway. You are looking roughly westwards towards Stanford and the southern end of San Francisco Bay.