Easter sepulchre. As part of the Easter liturgy, the blessed sacrament is removed from its usual place of reservation, and placed in an altar of repose, the so called Easter sepulchre. This is to represent the death of Christ, and the placing of his body in a tomb. The return of the sacrament to the high altar represents the resurrection of Christ.
In a modern-day Catholic church, this liturgy is still enacted; the sacrament is carried to the altar of repose at the end of the Mass on Maundy Thursday, and a vigil is kept over it through the night. The main church altar is stripped of all its furnishings, and no Mass is said on Good Friday. Then, on Holy Saturday evening, the host is reconsecrated, and the resurrection relived through the Mass.
The sepulchre is often found in the north wall of the chancel, a wide open space with a flat surface in an alcove. Sometimes, it forms part of a tombchest. It might be that Christ's tomb itself was reconstructed, and the sacrament place in the tomb. However, many churches do not have Easter sepulchres, and it seems certain that in some cases the altar of repose was outside the church.
The Easter liturgy was reintroduced into some Anglican parishes under the influence of the Oxford Movement in the late 19th century. An Anglican form of the liturgy was introduced in the 1980s, and is widely in use.