Ride up MacArthur from Canal towards the reservoir with its high fences and you'll pass the Georgetown Castle Gatehouse on your left, a sluice gate that lets water into a tunnel that leads to MacMillan Reservoir, near Howard University. If you recognize it from your dad's U.S. Army Corps of Engineers patch (as I did), you're spot on: the castle was "designed to represent the insignia of the Army Corps of Engineers from all four sides." You know, in case the one side wasn't enough.
If you keep going West on MacArthur and into the past 136 years and look backwards up the hill toward where the German Embassy is now, the view is this one:
Bikes have been on MacArthur (previously Conduit Road) for well over a century, for twice as long as cars (and pavement) have.
Not just gentlemen in top hats on their velocipedes; MacArthur hosted bike racing.
We have been riding and racing MacArthur for longer than anyone living can remember.