"For as long as humans have made towers, some have leaned. The Tower of Pisa started settling unevenly..."

"... on its shallow foundation not long after its third floor was added, in 1178. Despite the increasingly obvious problem, five more floors were built over the next two centuries; the ornate bell chamber was finished in 1372. In 1990, when the angle passed five degrees... [c]rews siphoned earth from underneath the building to mitigate the problem, though by then it was unthinkable to eliminate the lean entirely. Millions of tourists came to see the flawed structure every year.... In the fourteenth century, when the medieval traveller Ibn Battuta visited the Great Mosque of al-Nuri, in Mosul, he wrote that its curving minaret was 'splendid,' and affectionately referred to it as al-Habda, or 'the hunchback.' The mosque was destroyed in 2017, during the Battle of Mosul. UNESCO later surveyed locals about restoring it, and ninety-four per cent of respondents said that they wanted the minaret rebuilt 'exactly as it was.'..."

From "The Leaning Tower of New York/How a luxury condo building in Manhattan went sideways" (The New Yorker).