A friend of mine does contract work doing photos of high end houses for a large "expensive house" magazine (that is my name for it, I'd rather not say which one.) Most of the covers and most of the article shots of their "showcase" house are his. He gets to travel around the country doing shoots which, from your description, I think you would enjoy greatly. Note, that this absolutely does *not* make up the bulk of his income. He also does advertising shots (product shots, mostly) and I think other things.
So yes, there is a market for pictures of architecture. It isn't huge, but it is absolutely there. And you have to think creatively... not only are there magazines, but there are trade publications, books (both about a specific person and a location), advertising booklets (a pitch booklet for a design firm.)
And as for landscape work... There too you have to be creative. You can make a living doing that. If you go a direct-sales route, most people purchase pictures they have a connection with, which often means "local" pictures. You can mix in some of the "classic" places (I'd love to go to yellowstone, joshua tree,...) but you'll be surprised what people will buy because the picture means something to them.