Apache Point observatory is located above Alamagordo, New Mexico, not far from the National Solar Observatory in Sunspot, NM. Both of these observatories are at about 10,000 feet above sea level and overlook the basin that includes the White Sands Missile Range and White Sands National Monument. Apache Point is a very modern, private facility, but you can tour the grounds during the day. The location was selected because the airflow patterns help minimize atmospheric distortion. The larger scopes here are of the compact, boxy reflector type and the "domes" reflect this design. Much more info at http://www.apo.nmsu.edu/
At left is the "dome" for the famous Sloan Digital Sky Survey, which is a three-dimensional survey of a large part of our universe and a replacement for and a vast improvement over the old Palomar sky survey of the 1950s. In this case the whole building, which is perched out over the edge of the mountain, rolls toward you, completely exposing the scope to the night air At right (and at left below) is the dome for the NMSU 1.0 meter telescope. It is an alt-azimuth Ritchey-Cretien design employing many of the successful design innovations of the 3.5-meter telescope. Look how small this dome is compared to the 36-inch scope dome at Mt. Wilson. This reflects the compact design and mounting of today's scopes.
Above right and below is the "dome" (box is a better term today) for the Astrophysical Research Consortium 3.5 meter scope! While we were busy looking at hummingbirds, an employee about to go to lunch came out the open door and was kind enough to invite us in to see it. Thanks again!
Finally, a decent picture (below) of one of the "boxy" modern reflectors so you'll see what I'm talking about. The primary mirror was made using spin-casting technique, making it a hollow mirror and weighing only 1/5th as much as if made of solid glass equivalent. This allows the mounting to be very lightweight, too. It is a general purpose telescope designed to make observations at optical and infrared wavelengths. But it can also move quickly and precisely and has even tracked missiles! You can see how the building is crammed in around it and both the scope and building rotate around together. Only in altitude does the scope move independent of the dome. This makes the domes much smaller and simpler (thus cheaper) to build.