Never heard of back to backs? Neither had we till I started looking for a National Trust Cottage in Birmingham. The National Trust is a non-profit charity that preserves historical properties and has converted some of them into holiday cottages, using the income from the rentals to help support the Trust.
Built in 1802, the back to back houses were constructed to house the families of the growing factory-worker force in Birmingham, a center of the Industrial Revolution and manufacturing for England. Row houses, 3 stories high, with one room on each floor, were built 2-deep. Each floor had a window on one side and the back wall was solid, with another room behind it, facing the other direction.