Vista from the dome

Florence's Duomo (Cathedral) with it's giant dome is probably it's main sight. When they started building shortly before 1300, the Florentines decided they wanted a huge dome as the final piece of their new church, only no one knew how to construct such a giant thing. Nonetheless they started building, figuring that when they'd come to the dome, years would have passed and technology and science would have advanced far enough to make such a project possible. Although it took more than 100 years they were right, as in the beginning of the fifteenth century the genius Brunelleschi designed a self-supporting dome that could be constructed without scaffolding.
If you brave the steps and heights (at some points you look straight into the church from about 80 meters high) you can get on top of the dome and be rewarded with amazing sights like these.