Visible through a grille on the right of the entrance to the oratory, the cubicle holds not only the stone used by Catherine as a support for her head in her rare moments of rest, but also some important relics of the Saint, kept in a case hanging on the left wall: the round handle of the walking stick she used to support herself, the jar where she put herbal essences to ease the pains of the sick in the Santa Maria della Scala hospital, the lantern she used for night visits, part of her veil, and the silk bag in which her head was placed when it was brought to Siena from Rome in 1384.

In front of the grille is a marble statue of Saint Catherine in Ecstasy, sculpted in 1940 by Pietro Repossi, and behind this is a small cabinet containing the books listing the names of the members of the International Association of 'Caterinati', the followers of Saint Catherine. On the wall above are some ex votos donated by faithful who received grace after praying to Saint Catherine.