The Sororium Tigillum, which translates as the "sister's beam", was a wooden beam said to have been erected on the slope of the Oppian Hill in Ancient Rome by the father of Publius Horatius, one of the three brothers Horatii. Publius Horatius was required to pass under the beam, as if under a yoke, following the decision of the people's assembly not to punish him for the murder of his sister.
- John Henry Parker (1883). The Via Sacra. Excavations in Rome from 1438 to 1882. J. Parker. pp. 60–.
- http://latin.packhum.org/loc/914/1/26/3288-3296 Liv. 1.26