17. The Barley Barn, Cressing Temple

Source: http://esah160.blogspot.co.uk/2013/11/breaking-news-essex-county-council-in.html

This cathedral-like agricultural structure is the oldest standing timber-framed building in the world, built all the way back in 1220AD.

18. A&G Murray Mills, Manchester

Source: http://en.wikipedia.org/wiki/Fine_Spinners_and_Doublers

A monument to Britain's Industrial Revolution, the Mills of Ancoats drove the largest industry the word had ever seen in the early 1800s.