Is there a way to delete a building that you don't want anymore? I tried selecting a building and pressing "del" on my keyboard, which is the norm with RTS games, but it didn't do anything. Help!

next to your mini map on the left there are four buttons. The third button down is a x symbol which will delete any building you build

also - I think one icon up from the delete X - there is the undo command which you can use to undo constructing a building

While we're on the topic of buildings in Stronghold:
Defenitely use the SPACE BAR and maybe that button for *flatten landescape*,
I remember reading reviews of Stronghold back then and some reviewers totally missed out on the feature and thought that building a castle was dead hard in this game.
LOL I agree, if I didn't know I could make all buildings into flat squares when I'm building my "masterpiece" then I would've chucked stuff at my computer.
OH and I'm recalling the shortcut from memory, haven't had a chance to replay Stronghold recently yet.

LOL, I played this game when it came out and some time after that.
Then just as I bought it on Gog and was playing it I finally found out about that.
I accidently hit the space bar and then was like "Ahh! What happened?!?!?" then I was pressing keys and finally figured it out.
Would have came in handy a ton back in the day, especially building those damn walls in the corners and crap, always seemed to get attacked and think "yay, full proof castle" then the entire army would slip through a little crack I had left in the wall but I wasn't aware of because of the angle/terrain.

You can (right click, i think) and toggle a semi-flatten mode, where you get an idea of what is where but can still see. It's a good compromise.