The most famous terrestrial telescope is the 200-inch reflecting
Hale Telescope at Mount Palomar near San Diego. This was for years
the largest telescope in the world.
The Keck Observatory high on the Hawaiian peak Mauna Kea is more
modern.
But my own personal favorite is the Lick Observatory on Mount
Hamilton. If you live in the Silicon Valley, you can see the dome
gleaming in the sun from almost anywhere in San Jose or Sunnyvale.
The Lick Observatory is up a twisty windy little road, and the
telescope isn't large by modern standards - but it is beautiful and
historic.
See the links for some other choices.