Huron County Gaol
Erected between 1839 and 1841, this remarkably preserved building follows Jeremy Bentham's Panopticon design for prison construction, often found in mid-19th-century Britain and America. It features an octagonal central block, intended to ensure constant supervision of prisoners' activities. Two radial wings and wedge-shaped exercise yards surrounded by thick masonry walls completed the original design by Thomas Young of Toronto. Construction of this prison with its third floor courtroom enabled Huron to qualify as a district separate from London, with Goderich as its seat.
Plaque via Alan L. Brown's site Ontario Plaques. Full page here.