Do you really think you could build a tower without tensile reinforcement? The hoop stress on the base of a cylindrical tower is no joke, especially when made from something as dense as concrete…
I will plead not a professional engineer on the one. The Tower of Pisa and it’s less leaning cousins are thing, although Wikipedia informs me they were actually medieval and made of joined masonry rather than cast concrete, despite appearances. That’s the main reason I brought it up.