Patrimony of Saint Peter
Properly designates the landed possessions and revenues from various sources belonging to the Holy See up to about the 8th century.
Sometimes applied to the States of the Church (754-1870), here it is taken in the former sense.
Before the law of Constantine, 321, empowering the Church to acquire property, the possessions of the Holy See could not have been very considerable.
However, the first Christian emperor and the newly converted nobles, by their gifts, soon put the Church in possession of very large estates.
These large donations stopped about the year 600, due to the impoverishment of the wealthier Christian families brought on by the barbarian invasions.
In the time of Gregory the Great (590- 604) the pope might have been called the largest landed proprietor in the world.
The patrimony then embraced large farms, pasture lands, forests, even whole villages and towns.
With the estates (Latin: fundi) went the coloni or cultivators, who, though attached to the soil, were personally free.
Many of these estates bore the names of their original owners, e.g., Fundus Corneli, Fundus Pompilianus.
A number of these estates formed what was known as a massa.
A certain number of massae formed a patrimony, which often, in Italy at least, equaled an ancient Roman province.
The patrimonies were situated mostly in and around Italy, although there were some throughout the Orient, Dalmatia, Gaul, and Africa.
The most valuable were those in Sicily, the most numerous those around Rome.
Other patrimonies were situated near Naples, Gaeta, Tivoli, Ravenna, Genoa, etc.
All together were called the Patrimony of Saint Peter.
The revenue was devoted to the building and maintenance of churches, monasteries, hospitals, etc., for purchasing the freedom of slaves, and for relieving the needs of the people of Italy and elsewhere.
Saint Gregory called the Patrimony of Saint Peter the property of the poor.
New Catholic Dictionary