Modern Paris owes much of its downtown plan and architectural harmony to Napoleon III and his Prefect of the Seine, Baron Haussmann. Between 1853 and 1870 they rebuilt the city centre, created the wide downtown boulevards and squares where the boulevards intersected, imposed standard facades along the boulevards, and required that the facades be built of the distinctive cream-grey "Paris stone". They also built the major parks around the city centre. The high residential population of its city centre also makes it much different from most other western major cities.