Andong-si is a beautiful town which have a number of interesting local attractions. With only 1 night in Andong-si, we could only visit Hahoe Village and Bongjeongsa Temple.
To explore this beautiful town and all the attractions, you will need at least 2 nights in Andong-si given that the attractions are a distance from each other.
Try to go during the mask festival. It is great. Otherwise, consider skipping this city. Our opinion is that it is much over related.
There is "a traditional market" (not the one for tourists) and that is worth going.
Not much to do or see in Andong, but near the Hahoe Cultural Village which is very worthwhile to visit.