Yn ystod yr hydref 1788 aeth Syr Richard Colt Hoare, hynafiaethwr enwog o Wiltshire, i ymweld â'i ffrind, William Coxe yn Sir Fynwy. Aethant am daith o amgylch henebion y sir a chafodd William ei hudo gan:

'... the picturesque ruins of ancient castles memorable in the annals of history, and I was animated with the view of mansions distinguished by the residence of illustrious persons; objects which the sketches of my friend's pencil rended more impressive.'

Parhaodd ar ei deithiau ar ei ben ei hun ym 1799 gan deithio 1500 o filltiroedd mewn pum mis. Yn sgil hyn, lluniodd Coxe dwy gyfrol swmpus o'r enw 'Historical Tour of Monmouthshire'.