You know what I love about the Washington DC Subway system? The architecture is vast and open, it keeps it simple and makes it easy to find your way around. That was actually the intention of the architect if memory serves. Not as grand as, say, Moscow, but amazingly functional. Now take Park Street or Downtown Crossing... I can't count how many times I've given a tourist directions, or told someone in Park Street "Trains don't pick up people on this track, where are you trying to go?"
Harvard Square station reminds me of the former, wide open, and easy to navigate, at least from the main lobby.
When you pass the fair gates, there are two ramps, one going up and one going down, both clearly marked with the direction of travel. The lobby itself is large, and contains ample fair machines. There's a Dunkin Donuts, of course in a station this large, it would be weird if there *wasn't* one. With one of them behind glass, busway is very easy to find too.
There are also two alternate entrances/exits. One of these is at the far end of the upper busway, and another on Church St (someone please correct me if I'm wrong here, I'm not an expert on street names). I've used this station for long enough when I enter I am on autopilot, so I can't definitively say how easy (or not) navigation is from these entrances... though I can say there is ample signage throughout, and this station is nowhere the hot mess of the aforementioned Park St or Downtown Crossing.
One of the notes I have is there is one vertical TV screen in the lobby that contains the bus departures. The only other indication are the signs on the actual busways, which only display two busses at a time. It would be nice to have a little more signage. Not necessarily a large board like they have at South Station, but something larger than a modest TV screen.
The station is fairly clean, well, as much as you might expect from a large station in an urban area. There's no graffiti, and no excessive amounts of trash. There is a restroom, though don't count on it, I once needed to go, only to find, umm, an contemporary organic masterpiece on the floor. Also, the elevator by the busway more often than not smells like a public glass urinal (with camera to boot!). read more