Paris's elegant boulevards replaced whole neighborhoods.

The problem beneath the streets

By the mid-19th century, Paris’s narrow lanes were crowded, poorly drained and difficult to clean. Waste from homes often collected in cesspools or ran through gutters; rain could wash it into streets and waterways. Disease outbreaks made sanitation an urgent civic problem, not simply an issue of urban appearance.

When Napoleon III appointed Georges-Eugène Haussmann to reshape the city in 1853, sewer construction became part of a much larger rebuilding program. Haussmann’s engineer, Eugène Belgrand, helped design networks for both clean water and waste. The new sewers carried wastewater away from homes and streets, while pipes brought cleaner water into the city. The systems made sanitation depend on infrastructure people could not see, as well as on the boulevards they could.

Why rebuilding meant demolition

The old street pattern was not an easy place to install large pipes or move water through a planned network. New streets opened routes for construction, maintenance and traffic; beneath them, sewer lines could be laid and connected. Widening and straightening streets also made the city easier to traverse, but required cutting through existing blocks. Entire buildings—and, in some areas, established neighborhoods—were cleared.

The work unfolded over years, not as a single clean sweep. Property was acquired and demolished, and residents had to find somewhere else to live. The transformation made central Paris more orderly and better served by public works, but its costs fell unevenly: those displaced did not all return to the rebuilt districts, where rents and redevelopment could put housing beyond their reach.

A modern city with an uneven price

The sewer network helped turn waste removal into a citywide service rather than a problem left to individual households and streets. But sanitation and spectacle were built together: the broad avenues above ground depended on disruptive construction below it. Paris’s celebrated uniformity was not merely designed into the skyline; it was purchased through the removal of the city that had stood there before.