I have to be at the Nashville airport at 4:00pm, the Monday after 'Roo. What would be a must-see/must/do thing, in Nashville, before my flight?

So, I thought I was getting an early flight out on Monday, but now my flight is later in the day. What do y'all recommend doing for half a day in Nashville?

Also, is getting out of 'Roo hard, in terms of traffic? What time do people typically leave on Monday? I was thinking of leaving around 8am, getting to Nashville (hopefully) around 10am, and spending 6 hours there. Is that realistic?

I've never been, and I don't know what I should do for those 6 hours. Totally open to ideas!!