Architectural features Prince amends incorporating pillars (9)

I haven't cracked this one yet — but the brilliant team at Fifteensquared have:

P (abbreviation for Prince) + EDITS (amends), including MEN (pillars? I’m not sure how this works, except perhaps as in “pillars of society”). [UPDATE: Thanks to PostMark and FrankieG for pointing out that “man” can mean a rock pillar. I had a vague thought about that but couldn’t find it in Collins online; I should have checked Chambers.]