The towers go pretty high obviously, anyone tried to make a building that high?

10 stories at spectacle island is the highest

Pretty sure different settlements have different height limits.

I built a tower on red rocket roof that was roughly 10 stories tall. At Greygarden you can build high enough to get up on the bridge and build stuff on top of it.

It varies, settlement by settlement. Some you can go really high, others not so.

Hangman's Ally for example, I think is limited to just slightly lower than the surrounding buildings. Whereas, the aforementioned Spectacle Island has a ten story high limit.

beleive at Abernathy you can 20 or 21 stories

I always get as high as possible before I start building.

I found a new settlement, the Lighthouse one where you can go as high as the tip of the Lighthouse which is very high. I was higher than the Pyrdwen so I made a rooftop bar and drinking area.