In his online chat with us last night, Barry Strauss mentioned Fustel de Coulanges, The Ancient City, "one of the really great books on the Greco-Roman world – even though a lot of its ideas have proven wrong." La Cité antique (1864)
The book can be downloaded from the Internet Archive:
The ancient city : a study on the religion, laws and institutions of Greece and Rome
Or as PDF file from the McMaster University Archive for the History of Economic Thought.
Numa Denis Fustel de Coulanges (Wikpedia, handle with care)