  The area of Chajnantor, at more than 5000 meters altitude in northern Chile,
offers unique atmospheric and operational conditions which arguably make it the
best site in the world for millimeter, submillimeter, and mid-infrared
observatories. Long-term monitoring of the precipitable water vapor (PWV)
column on the Chajnantor plateau has shown its extreme dryness with annual
median values of 1.1 mm. Simultaneous measurements of PWV on the Chajnantor
plateau (5050 m) and on Cerro Chajnantor (5612 m) show that the latter is
around 36% lower under normal atmospheric conditions and up to 80% lower than
the plateau in the presence of temperature inversion layers. Recently, the
Government of Chile has consolidated the creation of the Parque Astron\'omico
de Atacama (Atacama Astronomical Park), an initiative of the Chilean Commission
for Science and Technology (CONICYT). This new Parque offers an opportunity for
national and international projects to settle within its boundaries, gain
access to an extremely dry site that is suitable for observations over a broad
spectral range, especially in the millimeter to mid-infrared wavelengths, and
benefit from operational and logistical support within a secure legal
framework.
