The Parthenon was finished in 432 BC and there's not one truly straight line in it. Every surface curves imperceptibly to counteract optical illusion; every column tapers and leans by fractions of an inch. It's been a treasury, a church, a mosque, and a powder magazine. In 1687 a Venetian mortar hit stored gunpowder and blew the interior out. What's standing is ruin. It's still the most-visited ancient monument on earth.
© Laurens R. Krol, CC BY 4.0, via Wikimedia Commons