A fun idea would be to embark on a mountain, build your towers into the mountain, and then shave the rest away. Leaving behind some nice natural towers!
A long, long time ago (pre-caverns, as they are now) I set about digging out a massive complex out of natural stone, leaving pyramids and obelisks
2 undug, down to leave just one
1 remaining properly underground layer through which I had the underground access between the various inner spaces and across to beyond the 'city limits' where I was forced to create the required infrastructure to support the dwarves to supoort the megaproject.
It was a lot of effort. And a lot of 'waste' (probably turned into crafts and mugs!) needed shifting.
Done again, I might choosing a geologically 'pre-carved' terrain and planning around such surface features, with maybe any surface building needed to extend the rubble back up into
structures beyond the original ground level, if I could stand it being 'faked' like that, to share the effort between intensive digging efforts and intensive building efforts...
Also, these days, I'd have to cater for a whole lot more dangers occuring whilst in the midst of the megaproject. That old project, I discovered the need to put a (one level) wall around the entire lip of the dig-site to prevent marauding archers from raining death/inconvenience down upon my army of quarrymen (as well as the well-practiced set of protected side entrances (at all cardinal and diagonal map-edges) down into the more traditional underground complex, where I had already added all my traditional anti-interloper tricks with traps (not then wagon-blocking) danger-route diversions and sally-ports aplenty).
More recent not-quite-megaprject versions of this sort of thing has had to incoporate at least a
temporary roof across the workings to prevent flying hostiles, as well as the more involved climb-proof walls, etc. Some of these features are verging upon the kiloproject scale, in ther own right, though. (One could just turn off invasions, etc, but I don't like doing that.)
1 Or maybe two, I had reflecting-pools in the plan, which needed another 'Z-1' of space above the undiggable layer...
2 3x3 with hollow stairway cores leading to 'skyway' bridges (two 10x1 bridges, mostly, between the various obelisk 'tops', just below the actual spire roof
3, just below the original lost soil layer that was the first thing to be strip-mined away.
3 While I insisted on natural (yet smoothed, wher not ramped) rock throughout almost every part of the potential necropolis, I replaced the spire-tips with
electrum standalone ramps (and the 8-slopes the next level down for the main central pyramid). It would have looked great in Stonesense! Although I never did use that back then (and not so much since).