Gettysburg battle grounds
I just discovered this little gem, great for a leisurely ride, if you like to take in some sightseeing and exploring with your biking. A little over 20 miles with lots of short but decently steep hills, and a lot of fun to do on a nice day. If you are a history buff or/and a dork (definitely AND for me...), this is a fantastic opportunity to see history and imagine it come to life.
The best way to do it is to follow more or less the path for the "auto tour", with detouring rambles as you please. If on a weekend, best to start early, as the parking lots fill up very quickly.
Here's a shot of the route we took: