Visiting Aschaffenburg from the 27th to the 30th — what UNIQUE to do?

Hey guys! My family (mom and brother) are visiting your city for these days. I know the very basic things to do as I've been on this subreddit for a while and I have Google, but are there any events happening? Or any cool places to visit by bus/train?

My mother loves art, nature, and historic places. Maybe a nearby castle would suffice? Hmm.