Depending on what's considered old.
Alien is pretty good. The sets and monster design are incredible! Can't go wrong with Giger-esqe aesthetic.
Laurence of Arabia is long, but absolutely beautiful. It may take a while to finish it, but it's more a painting than a movie in some instances.
If animated movies are allowed.
Can't go wrong with early Ghibli works. The worlds created are remarkable, each detail within makes sense in the context of it's surroundings.
Nausicaa of the Valley of the WInd has some remarkable shots.
Castle in the Sky has great story pacing and outstanding music.
If you want something relatively light and funny.
War Games isn't old per se, but it has the most accurate computer hacking i've seen in any film.