The original entrance to Arlington National Cemetery is McClellan Gate, the rear of which is seen here. Someday I'm going to have to walk around to the other side of it to see the front. This was as close as we got, so I didn't see too much of it. The gate dates back to 1879, so it's been there for a good long time now. I'm sure it will be there when I get back to DC.
If you look beyond the gate, you can see the Pentagon way in the background.