Pope Innocent III's dreams must have been troubled ones: the thought of floating and drowning babies in the Tiber River prompted him to put an end to the all-too-common practice of infant exposure ((infanticide by abandonment), which was rampant in 12th-century Rome.

On the side of Ospedale Santo Spirito along its external wall, a small structure sealed off by a grid contains a wheel that was originally used to receive unwanted children. The building that it is part of is the ancient hospital, originally built in 1198 on land owned by the "Schola Saxonum" and run by an order from France known as the Order of the Holy Spirit. The building has been restored and rebuilt countless times in history, but, thankfully, this small unusual element was somehow preserved.

The wheel provided the cover of anonymity and, hopefully, a better future for unwanted children. In medieval and Renaissance Europe, it was common for unwanted children, especially girls, to be abandoned. War, famine, plague, extreme poverty, and social pressure were some of the reasons that children might be left behind.  Instead of abandoning an infant to the elements, mothers could place them into the door and ring a small bell to alert the nuns. The children would be marked with a double cross on their left foot and put up for adoption or raised by the order. Another box nearby welcomed alms and donations for the service that the order provided. Similar services existed elsewhere, such as the Ospedale degli Innocenti (Hospital of the Innocents) in Florence.

Children were registered in the archives with the expression filius m. ignotae, where the abbreviation m stood for mater (mother). Over time, this gave rise to a common insult in Rome, "filius mignotae", where "mignotta" became a common slang word for a whore. The number of exposed infants is even said to have shocked Martin Luther, in his 1511 visit to Rome.