That was Namsan Tower when I was stationed in Seoul in 1988. Looks the same (assuming that's the tower in your photo). The US base back then was the old Imperial Japanese Base, which I understand was transferred to the ROK government decades ago; the bachelor junior officer's quarters I lived in was built by the Japanese and "upgraded" by the Army Corps of Engineers.

The photos of Seoul are so clear, Gillian! In 1988 the ROK government had to institute an odd/even driving rule and shut down local factories to clear the air for the 1988 Summer Olympics. We could actually see Namsan Tower! (Most winter days it was barely visible, what with most home heating still via charcoal.)

My father was stationed in Seoul in 1953, during the war. When he visited (with photos from back then) the changes in the city were astounding. Looking at your photos of buildings like KNU, I suspect I would have the same reaction now.