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^[1] 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 to not to punish him for the murder of his sister.

According to Livy,^[2] writing at the end of the 1st century BC, the Sororium Tigillum^[3] remained intact in Rome until his day, having been maintained at the public expense.