Lime kiln

A lime kiln burned limestone or chalk to make quicklime for mortar, plaster and limewash. Medieval kilns ranged from simple clamps of stone and fuel heaped under turf or clay to the more usual flare kiln, a stone- or clay-lined bowl with one or two flues, loaded and fired as a single charge, usually with wood. Many were dug beside castles, churches, abbeys and town walls to supply mortar for building. Lime was also used in preparing hides for tanning.

Sources: historicengland.org.uk