Cubiculum

: cubicula) was a private room in a domus, an ancient Roman house occupied by a high-status family.

It usually led directly from the atrium, but in later periods it was sometimes adjacent to the peristyle.

It was used for the functions of a modern bedroom, sleep and sex, as well as for business meetings, the reception of important guests and the display of the most highly prized works of art in the house.

[2] The private nature of the cubiculum made it a place for contemplation and religious observance, especially when illicit.

According to the Actus Silvestri, Constantine the Great first learned of Christianity in his cubiculum and fasted there for a week before his first confession and baptism.