Crumlin (Welsh: Crymlyn) is a town, community and electoral ward in Caerphilly county borough in South Wales.

It is situated in the Ebbw River valley, 5 miles (8 km) west of Pontypool, within the historic boundaries of Monmouthshire.

Kelly's Directory of South Wales (1895) noted that Crumlin was "a secluded village, scarcely known to any beyond the few persons resident there".

It considered Crumlin one of the most picturesque spots in the county, surrounded by natural features of "unsurpassed loveliness".

Work by the designer and contractor Thomas W. Kennard commenced in autumn 1853, and the viaduct opened in June 1857 for the Taff Vale Extension to the Newport, Abergavenny and Hereford Railway.

Plans for preserving the viaduct were discussed, but the poor state of repair made this impossible, and it was dismantled between 1966 and 1967.

[3] Even while demolition work was in progress, scenes for the film Arabesque, which starred Sophia Loren and Gregory Peck, were shot on it.

The canal was built from Crumlin southwards towards Newport, opening in 1794, but not completed at Fourteen Locks until 1799.