Today I set out from the Harvard Center for Astrophysics in the afternoon, hoping to get back in time for the last talk of the day. I didn't make it. I got a little bit lost, and the second-to-last speaker bailed. I had a good time exploring town though, and seeing the sights around Cambridge.
My route:
http://www.mapmyrun.com/run/united-states/ma/cambridge/699127139072963347 I was out for 1 hour 17 minutes. When I got back, I showered (they have a shower in the men's room. For bike commuters?) and everyone was packing up to go to dinner. So we went.