[quote=Legend]
I either imagine a field with building in the distance, or a room.
[/quote]

Let me describe what I normally think of in more detail. Picture a moderately sized courtyard that's covered in grass and training things. Bordering that is stone about 1.5 metres wide all around, and then it's surrounded by a structure. The courtyard is open to the sky, which accounts for the weather. We probably do need to agree on what the bases look like so as not to cause later confusion.