The Leaning Tower of Pisa is undoubtedly the most famous of all towers that lean at alarming angles, but it is not the tallest. That credit belonged to the Leaning Tower of Zaragoza, sometimes called by its Spanish name, Torre Nueva, in Spain. Unfortunately, the tower no longer stands.
At 80 meters, Torre Nueva was the icon of Zaragoza. It was also the highest Mudéjar-style tower ever built.
Source: amusingplanet.com