Newchurch (Welsh: Yr Eglwys Newydd ar y Cefn, meaning "new church on the ridge") is an extensive rural parish and small hamlet in Monmouthshire, south east Wales.

In the early 12th century the Newchurch area was known as Plataland and was given by the Marcher lord of Striguil, or Chepstow, to Tintern Abbey.

Cas (or Castell) Troggy is a small ruined fortified hunting lodge or manor house built by Roger Bigod around 1303.

It is located within Newchurch parish, beside the Troggy (or Castrogi) Brook and the old road between Chepstow and Usk, on the northern slopes of Wentwood at Pen y cae-mawr.

[3][4] The 16th century antiquarian William Camden incorrectly referred to the ruins as Striguil, a mistake repeated on some later maps.