The apse is frequently surrounded by an aisle that runs behind the altar. This aisle, known as the ambulatory, led to additional tiny chapels known as radiating chapels or chevets. Of course, there are several variants on this common medieval church architectural basic components. For example, some churches have a single large apse but with several smaller aisles running off of it, while others have multiple small apses without any one being particularly important or prominent. However, whatever their size, all these aisles share a common purpose: to provide access to the sanctuary for priests and congregants who are unable or unwilling to climb the stairs leading up to it. In French pilgrimage churches, the ambulatory is where pilgrims went to be blessed by saints' relics. It usually consists of a series of rooms or "chapels" opening onto it, used for prayer meetings or private conversations with the priest. In addition, some of these rooms were also used as sleeping quarters by pilgrims. These rooms are called "radiating chapels" because they radiate out from the ambulatory like the petals of a flower. The word "ambulatory" comes from the Latin ambulare meaning "to walk about". In Christian churches, the term refers to a space surrounding the nave (the central part of the building where people worshipped) where pilgrims went to pray for healing or other benefits.