Most towers worth visiting have them.

Yes. Almost every major tower with tourist traffic offers audio guides, informational plaques, or both. The Leaning Tower of Pisa, the Eiffel Tower, the CN Tower—they all have something. Geology gets less attention than history, but it’s usually covered if the tower’s structure or location is geologically interesting (e.g., the Leaning Tower’s tilt is because of soil).

If you’re going to a smaller, less famous tower, check their website. If they don’t mention audio tours or plaques, they probably don’t have them. In that case, just read Wikipedia beforehand and look at the view.

The audio tour is worth it if you’re into context. Otherwise, the plaques will do.