There is no single architect to credit. The Parisian apartment block is a typology that was codified under the prefecture of Baron Georges-Eugène Haussmann, between 1853 and 1870, when Napoleon III commissioned the wholesale renovation of central Paris.
The elevation obeys a strict, repeatable composition. The ground floor is a rusticated stone base given over to commerce, with large arched openings. The first floor is a low mezzanine, an intermediate level historically used for service. The second floor, the étage noble, has the highest ceilings, the largest windows, and a continuous wrought-iron balcony that runs the full length of the building. The third and fourth floors are intermediate residential storeys with simpler window frames and individual balconettes. The fifth floor takes a second continuous balcony, slightly less ornate than the one at the second floor, marking the run of the cornice. Above the cornice, a mansard roof at forty-five degrees houses the chambres de bonne for staff and modest tenants. Every facade is built in cream-coloured Lutetian limestone, quarried locally in the Île-de-France. Cornice heights are aligned across the boulevard regardless of who designed the building behind, typically twenty metres on streets wider than twenty metres. The fenestration follows a regular bay rhythm, and the two balconies act as horizontal datums that bind the elevation into the larger urban frontage.
Some sixty percent of central Paris was rebuilt on this template within twenty years. The result is the most uniform urban fabric of any major European capital, and one of the most aggressive acts of state-led design in history. The Haussmann block is less a building than a regulatory diagram made of stone.