As we travel the western states, we inevitably come across some of the great astronomical observatories, usually on mountaintops in pine/fur forests under clean, clear air with wonderfully dark skies. Both classic late 19th/early 20th century and more modern telescopes are featured. All of them have, in their time, redefined our understanding of the universe and it was a privilege to see them, even if was daytime. And there are more we haven't been to yet!
Take a tour using the links below. I've arranged the links generally in order of older to newer facilities, so you can see the change in telescope size and engineering/optical technology over the centuries. The McDonald Observatory's scopes span much of the breadth of this development, but I could not get photos of all three major scopes.
Because the NSO is dedicated to solar observing, it has unique design demands that aren't comparable to the night-time astronomical observatories, so I stuck it at the end by itself.
National Solar Observatory