Cattedrale di Santa Maria del Fiore

Friday 18 August ~ Florence
First stop was the magnificent Cattedrale di Santa Maria del Fiore, which we had stumble-bumbled upon the previous evening.

Because we didn't have our act together to pre-order tickets, we waited in line for almost an hour, along with at least a thousand others who also had not done their homework.

However, once we were admitted into the magnificent cathedral, we were informed that the FREE (!) English language tour would begin in a few minutes! We therefore enjoyed a delightfully informative tour by a young French art student, mostly focused on frescos.

Dante Alighieri

Construction of this once-largest-in-the-world cathedral was begun in 1296, and completed structurally in 1436.  The duomo remains the largest brick dome ever constructed. The physics of how to accomplish such a feat - in the 13th century - are astounding! 
To read about it: https://en.wikipedia.org/wiki/Florence_Cathedral

P.S. There you can also see photos that are better than mine!