Im only in Korea for a day. Any recommendations on what to do in such short time?

hello! this summer I’m going to be stopping by south Korea as a long layover. about 22h first layover and then on the way back I have a 13h layover.

I land in Korea in the afternoon so I would probably don’t have much time to turist around. I have a few plans but I would love recommendations on what I could do in such limi time!