  Significant advances in science always take place when the state of the art
in instrumentation improves dramatically. NASA's Chandra X-Ray Observatory
represents such an advance. Launched in July of 1999, Chandra is an observatory
designed to study the x-ray emission from all categories of astronomical
objects --- from comets, planets, and normal stars to quasars, galaxies, and
clusters of galaxies. At the heart of this observatory is the precision X-Ray
optic that has been vital for Chandra's outstanding success and which features
an angular resolution improved by an order of magnitude compared to its
forerunners. The Chandra mission is now entering its 13-th year of operation.
Given that the Observatory was designed for a minimum of 3 years of operation
testifies to its robust and carefully thought out design. We review the design
and construction of the remarkable telescope, present examples of its usage for
astronomy and astrophysics, and speculate upon the future.
