Astrophysical Observatories

Keck Observatory is a joint effort of Caltech and the University of California, consisting of twin 10-meter telescopes, Keck I and Keck II.  
  Caltech's Palomar Observatory, in San Diego County, is home to the venerable Hale 200-inch Telescope, as well as the 60-inch instrument, the 48-inch Samuel Oschin Telescope, and an 18-inch Schmidt camera.
The Combined Array for Research in Millimeter-wave Astronomy (CARMA) is currently the world's most powerful telescope at millimeter wavelengths.  
  The Owens Valley Radio Observatory (OVRO), near Bishop, California, is home to a number of Caltech-operated radio telescopes.

The Chajnantor Test Facility in northern Chile enables experiments in cosmic microwave background observations.
  The Caltech Submillimeter Observatory is one of the world's premier submillimeter telescopes.

The Laser Interferometer Gravitational-Wave Observatory (LIGO) is a pair of four-kilometer-long laser interferometers designed to detect gravitational radiation.

[Image credits: Keck - Rick Peterson; Palomar - Scott Kardel; CARMA - Peter Teuben; OVRO - Oliver King; Chajnantor - CBI Project; CSO - Jacob Kooi; LIGO - LIGO Laboratory]