The Uffizi sees up to 10,000 visitors daily, so not many locals often hang out there. But the few people you meet who've never stepped inside recognize that they, well, SHOULD. Apart from the incredible art collection, the building has long history—the name "uffizi" originates from "offices," since it housed the offices of the Florence magistrates.
Botticelli, Giotto, Titian, Raphael, Leonardo, Michelangelo—are you getting why this is an important place yet? This houses one of Europe's most impressive art collections which explains the eternal queues outside. Beyond the Italian masters, you'll find works by Rembrandt, Albrecht Dürer, Rogier van der Weyden, Pieter Bruegel the Elder and more.
Hours can vary depending on seasons. Book to skip the (longer) line; you'll still have to wait in another one, but it moves faster.