Final answer:
Baron Georges-Eugène Haussmann is most closely associated with the re-building of Paris in the mid-nineteenth century, as commissioned by Emperor Napoleon III. His transformation of Paris included wide boulevards, improved sanitation, and the introduction of gas lighting, impacting the city's architecture and social structure.
Step-by-step explanation:
The individual most associated with the transformative re-building of Paris in the mid-nineteenth century was Baron Georges-Eugène Haussmann. Appointed by Emperor Napoleon III, Haussmann's mission was to modernize the city, which was at the time plagued with narrow, medieval streets and poor sanitation.
The city's transformation included the creation of wide boulevards, parks, and new housing arrangements to mix social classes within the same structures. His work also addressed sewage, and the introduction of gas street lighting gave rise to Paris's moniker, 'the city of lights.'
Haussmann's plans for the city were controversial, as they necessitated the displacement of the urban poor and the destruction of old neighborhoods. However, the resulting architecture and urban design became a symbol of modernism and were extensively represented in Impressionist art. This period of extensive urban renewal has left a lasting imprint on Paris's landscape, making it a global model for urban planning and renewal.