Hercules Langford Rowley PC was an Irish politician and landowner.

Summerhill House was a 100-roomed Palladian house in County Meath, Ireland which was the ancestral seat of the Viscounts Langford and the Barons Langford. Built in 1731, it was likely designed by Sir Edward Lovett Pearce and completed by Richard Cassels in the Palladian style, although Sir John Vanbrugh, who was related to Pearce and with whom he trained, is thought to have also influenced the design of the house, which could be seen by the great arched chimney stacks and the palatial grandeur and scale.