I’ve been doing a lot of bicycling this summer. I have a hybrid bike that I bought when my daughter was on the high school cross country team; I’d ride and she’d run. 
Fairfax County has a lot of bike paths and I’ve been riding on a few of them that are accessible from my house. Recently, I discovered the Cross County Trail. I pedaled down to the Lorton Workhouse (an old prison) and got on the trail there.
Not an auspicious beginning, but it got better. There’s lots of old stuff along the way.
Crossing the road, I look over and see the remains of an old railroad bridge.
The path improves and I come across this bridge:
It’s a “barrel vault” bridge built by the prisoners in 1946 and crossed over a spur of the Lorton & Occoquan Railroad. It is the only masonry and brick arch bridge of its kind in Virginia. I was a bit surprised to find the ruins of an old boxcar just a bit more down the path.
40 foot wooden boxcar…not much left of the wood; but the frame is there. It’s a bit hard to take a shot through the fence. Remember what the path looked like where I got on? Take a look at this bridge on the path.
There’s a gated community along the way, and right next to the old prison.
Not sure if the guard towers are still manned. The path goes right past the old walls.
There’s a few very civilized crossings, complete with warning signs telling you to get off your bike.
Other parts of the trail have rougher crossings.
Anyway, it makes for a very pleasant bike ride!