Watch where and how you go. The locals tolerate the street people, who seem not to hussle you, but watch carefully the movements when going by. The college students get a free run most times to loosen up downtown and then have a party type on the streets, apparently without a lot of hassle. Do not get in a fight.
If you're going to be exploring Massachusetts Street, there are a plethora of parking meters on Mass St. However, on Vermont Street (one block away), there are two two-hour parking lots (on the 800 block and on the 900 block). Trust me though, they mean business when they say two hours. The meter maids will mark your tires and write you a ticket if you're there more than 2 hours. The ticket, last time I got one, was $2 and they're more of an annoyance, but still....
If you do get a ticket, there are these little yellow boxes conveniently placed around the downtown area for you to deposit your payment for the ticket. Convenient, no?
The local power company has a small hydro facility right on the Kaw River in downtown Lawrence. People tend to think of it as benign and slow-moving, but the river has its danger. Some fisher was wading in midstream when he got caught up in the current, was swept away and drown.
Now, that would be really depressing. It's not the way to go. I mean, if you are going to drown, at least you should drown in the ocean - or some other respectable body of water - and NOT in the middle of Kansas.
Incidentally, this is the ONLY hydroelectric facility in the state of Kansas.
If you are going to be near KU at all--mind the parking signs! I parked on campus and got this lovely parking ticket, which I never paid (oops)--trust me, it wasn't the first time.