From the top of Siena's Duomo

Il Campo and the Tuscan beyond. All from the top of an unfinished feat
of architechural integrity. They were planning on building a basilica
to rival the Vatican's St. Peters until the plague hit and wiped out
half of the population. The building was never finished an you can pay
a few €€ to climb to the top of what still stands unfinished.
Pretty amazing.