...but seriously...
I would imagine you'll be staying somewhere near the sports complex on South College Street (route 896) south of the railroad tracks where there are fields, a stadium, an ice skating arena, a defunct GM assembly plant, a hotel complex and not much else to speak of. There's something for everyone on Main Street a few blocks north of there (and several off-street parking lots).
Someone mentioned Winterthur, which is one of the local crown jewels, but it can be blazingly hot in July. The Hagley Museum is a little more shaded and cooler down by the Brandywine River and is the site of the original DuPont gunpowder mills and one of the older DuPont homes, where you can take a nice stroll by the river and learn how to make (and test) gunpowder. You will burn most of a day at either.
If you like to get outdoors and cool off, my favorite place on planet earth is further up on North College street which heads into the White Clay Creek State Park. First, you put on something that you can get wet in, and bring a towel. Pick up some sandwiches and drinks and head north on North College from Main Street until you're not sure you are really on a road anymore, and it becomes Creek Road. There's a little parking area at around 2:37 in this video:
https://www.youtube.com/edit?o=U&video_id=2YjA106gq8Y
Pull into that parking area and take the trail a little less than a quarter mile to the creek, where there's a big cool, wet reward awaiting you. Or, just keep going along Creek Road to the parking lot at 7:09 in the video, and there are a couple of trail heads there (including the one I come into the parking lot in that video). If it has rained in the last day or so, it can be a little muddy on the trail, but still worth it.
If you do go out in the woods, it's a good idea to spray your lower legs and shoes with insect repellent, check carefully for ticks afterwards, and don't approach any raccoons (if they're out in the daytime, we have a few rabid ones). Nothing to be paranoid about, though.
For "maximum Newark", lunch or dinner at the Deer Park Tavern (on the deck or inside if it's too hot) is probably the mandatory Newark experience. There's been a tavern there forever. The local legend is that Edgar Allen Poe stopped in on a trip from Philadelphia to Baltimore, got sick, and put a curse on the place, hence the "raven" themed decor. Come to think of it, it's a good place to stop after a ride or hike along Creek Road (which is also the local haunt of the perennial 'Hook Man' https://en.wikipedia.org/wiki/The_Hook ).
Oh, yeah, have a cheese steak - Malin's Market (just across the street from the McDonald's on S. College (896) as you come in from I-95) makes good ones, as does Margerita's on Main Street (or Capriotti's or Claymont Steak Shop). Keep it simple - fried onions, provolone and ketchup is fine (or mayo if your doctor says it's okay).
If you find yourself deeply enamored of Newark and in need of souvenirs, stop in at the National 5&10 on Main Street for a wide range of Delaware themed athletic wear and other weird Blue Hen stuff. The University of Delaware is one of the only campuses where you'll find the mascot being served for dinner.
Or, just take a stroll around campus. Near the chemical engineering building off the main mall, you'll find a large metal statue of a Blue Hen. The legend there is that if a virgin walks past it, it will fly. Try it out.
(oh, and that was early spring... it's a lot greener down there now)
= new reply since forum marked as read
