Siena Italy

The Siena Cathedral (Duomo), begun in the 12th century, is a masterpiece of Italian Romanesque-Gothic architecture. Its main façade was completed in 1380. The original plan called for an ambitiously massive basilica, the largest then in the world, with, as was customary, an east-west nave. However, the scarcity of funds, in part due to war and plague, truncated the project, and the Sienese created a subdued version from the original plan's north-south transept.
The east wall of the abandoned original folly of a nave still stands; through an internal staircase, visitors can climb for a grand view of the city.