The imperial constitutions still in force in Justinian’s reign, part of the body of Roman law later called the Corpus iuris civilis. It preserves Emperor Zeno’s building law for Constantinople, the first detailed building code of a medieval city.
Zeno (reigned 474–491) addressed his constitution to Adamantius, prefect of the city, after fires and disputes had shown the need for fixed rules. It survives as Book VIII, title 10, law 12 of the Code, and Justinian extended it to other cities in a later novel.
The law sets a clear gap of twelve feet between new houses and their neighbours, limits the height and projection of balconies, forbids blocking a neighbour’s view of the sea within a hundred feet, and regulates the small shops set between the columns of the great porticoes, which were to be kept small and faced with marble so as to adorn the city. It passed into the later Byzantine law books and, through them, into the building customs of the Balkans and Russia.
The book, part by part
I VIII.10.12: the constitution of Zeno
Twelve feet between houses; balconies; views of the sea; shops in the porticoes.
Rules: Twelve feet between houses