Lychnoscope
A small, low-level window set into the sidewalls of medieval European churches, often found in smaller churches, and is typically left unadorned with stained glass or decorations. Its purpose remains uncertain, with theories suggesting that it may have been used to allow lamplight to shine outward during nighttime worship, provide a view of religious services for those who could not enter the churches, or to improve ventilation. Although sometimes mistaken for a leper window, it was not necessarily intended for individuals with contagious illnesses.