Blondel was able to profit from the massive redevelopment of central Paris instigated by the emperor Napoleon III, and masterminded at more a detailed level by the Baron Haussmann.

The new broad streets and avenues called for the construction of many new buildings, featuring the artistic-heroic style of the Second Empire.

Blondel had a long association with banker Armand Donon, with whom he was involved in numerous real estate developments.

A surviving trace of these block concessions can be found in the Journal des débats (newspaper) of 8 July 1868 which includes the list of real estate transactions for Paris,[9] together with the relevant title deeds lodged with the Crédit Foncier de France (national mortgage institution) having a total value of 398 million francs.

[10] On 29 July 1895 Blondel was condemned for bankruptcy by a local court, in respect of indebtedness totalling slightly more than 25 million francs.