On May 15th at the rites of Argei 6 Vestal Virgins walked a route to a bridge on the Tiber.
They would stop along the way at 27 shrines.
At each of the shrines they would pick up a straw man.
Once they got to the bridge they would cast these straw men into the river.
It is thought that these straw men replaced old men who were sacrificed to Saturn (who, among other things, was the God of Old Age and so naturally would want to have old people sacrificed to him).