A chapel is a holy place or area of worship, sometimes small and attached to a larger institution such as a large church, a synagogue, a college, a hospital, a palace, a prison or a cemetery, sometimes large and unattached to another building.
Architecturally, a chapel may be a part of a large church set aside for some specific use or purpose: for instance, Gothic cathedrals typically have a "Lady Chapel" in the apse, dedicated to Mary; parish churches may have a "Blessed Sacrament Chapel" attached to the main church where the Eucharist is kept between services.
In the Catholic Canon Law a chapel, technically called an "oratory," is a space dedicated to the celebration of services, particularly Mass, which is not a parish church. This may be a private chapel, for the use of one person or a select group (a bishop's private chapel, or the chapel of a convent, for instance); a semi-public oratory, which is partially available to the general public (a seminary chapel that welcomes visitors to services, for instance); or a public oratory (for instance, a hospital or university chapel).
The word chapel is in particularly common usage in England, and even more so in Wales, for many non-Anglican Protestant church buildings; and in Scotland and Ireland many ordinary Catholic churches are known to locals as "the chapel".
Chapels are generally non-denominational when part of a non-religious institution.

Notable chapels

In Britanny (France) each village even very small, has is own chapel. Nowadays, they are only in service once a year for the local "pardon" which celebrates the saint to whom the chapel is dedicated. To permit some pretty of them to be better known, in the area of Pontivy, each summer, modern art is presented in a twenty of chapels. See details on : [1]
Church
Sacri Monti