A loop window (also called an arrow slit window) is a long, narrow, vertical opening cut in a medieval wall, parapet or fortification for use by archers.
While there were earlier institutions that housed the 'insane,' institutionalisation as the mechanism to treat (or contain) madness was essentially a 19th century phenomenon.
At the start of the 18th century London's Bethlem (later called Bedlam), which had capacity for 100 inmates, was the only public asylum operating in England. A second public charitable institution was opened in 1713 in Norwich. From the mid-18th century the number of public, charitably-funded asylums grew.
Partly as a result of the lack of state facilities, private madhouses proliferated in 18th century England. Licensing legislation was introduced in 1774, which saw 16 private institutions recorded in London.