Erba-Odescalchi, or Odescalchi is the name of a Roman aristocratic family.
This family is supposed to be descended from Enrico Erba, Imperial vicar in Milan in 1165. Alessandro Erba married Lucrezia Odescalchi, sister of Pope Innocent XI, in 1709, who is believed to have been descended from Giorgio Odescalchi (Jesuit at Como in 1290). The title of Prince of the Holy Roman Empire was conferred on Alessandro in 1714, and that of Duke of Syrmium in Hungary in 1714, with the qualification of Serene Highness.
The head of the family now bears the titles of Prince Odescalchi, Duke of Syrmium, Prince of Bassano, and others, and he is an Hereditary Magnate of Hungary and a Grandee of Spain. The family, which is one of the most celebrated in Italy, owns the Palazzo Odescalchi in Rome, the famous Orsini-Odescalchi castle in Bracciano, as well as large estates in Italy and Hungary.
The castle in Bracciano, although now belonging to the Odescalchi family, was originally an Orsini fortress until it was sold due to family debts.