Between the Visigothic sack of Rome in 410 and the deposition of the last Western emperor in 476, imperial authority in the Western Roman Empire disintegrated under repeated invasions and internal collapse. Cities that had depended on imperial taxation and administration lost the means to maintain aqueducts, paved roads, drains and gridded street systems. Populations shrank dramatically; Rome itself fell from perhaps a million inhabitants at its height to a few tens of thousands.
It ended the classical tradition of large, serviced cities in the West and opened centuries in which towns were smaller, more rural and locally defended, with planning knowledge largely lost until its medieval and Renaissance revival.
See it on the timeline →