Catalan vault
The Catalan vault (Catalan: volta catalana), also called thin-tile vault, Catalan turn, Catalan arch, boveda ceiling (Spanish bóveda 'vault'), timbrel vault or timbrel arch, is a type of low brickwork arch forming a vaulted ceiling that often supports a floor above. It is constructed by laying a first layer of light bricks lengthwise "in space", without centering or formwork, and has a much gentler curve than most other methods of construction.