County Monaghan on Wikipedia.

Ballinode. © Jack Storey.
Ballyalbany, Presbyterian Church. H 674 353. © Jack Storey. Another view, showing the results of renovation or re-decoration, © Gerard Close (2015).
Ballybay, Christ Church (Church of Ireland). © Jack Storey.
Bawn, St. Patrick (R.C.). © Karen Grace.
Braddox, Presbyterian Church. © Jack Storey.

Carrickmacross, St. Joseph (R.C.). From an old postcard in Reg Dosell's Collection. Link.
Castleblaney, 1st Presbyterian Church (1787). H 825 204. St. Maeldoid (CoI, 1811). H 828 195. The Immaculate Conception of the Blessed Virgin Mary (R.C., 1854), more commonly known just as St. Mary's. H 828 191. All © Gerard Close (2015).
Clones, St. Tighernach (CoI). H 500 258. Sacred Heart (R.C.). H 500 267. Presbyterian Church (1858). H 502 259. All © Gerard Close (2016).
Clontibret, the Presbyterian Church at Legnacreeve. © Jack Storey. St. Colman (CoI). Another view. Both © Malcolm Totten.
Corracrin, St. Patrick (R.C.). H 675 410. © Gerard Close.

Drum, Church of Ireland (Anglican). © Jack Storey.
Drumsnat, an early monastic site, and the burial place of two of Oscar Wilde's sisters. © Jack Storey.

Emyvale, the Donagh Oratory. H 677 439. © Gerard Close.
Errigal Trough, Church of Ireland. © Jack Storey.

Glaslough, Donagh Parish Church. © Peter McCrodan.
Glennan, Presbyterian Church. © Jack Storey. St. Mary (R.C., 1837). H 707 421. © Gerard Close (2011).

Kileevan, St. Laebhan (CoI). H 539 256. © Jack Storey.
Kilmore, the Parish Church. © Malcolm Totten.
Knockconan, St. Joseph (R.C.). H 674 460. © Gerard Close.

Monaghan.

Newbliss, Newbliss Presbyterian Church. H 567 238. © Jack Storey. Newbliss Church of Ireland. H 562 230. © Malcolm Totten.

Smithborough, Presbyterian Church. © Jack Storey.
Stonebridge, Presbyterian Church. It dates from 1830, although the congregation was founded in 1700. H 542 283. © Jack Storey. Another view. © Gerard Close (2018). Link.

Tedavnet, Catholic Church. Another view. Interior view. All © Janice Bacino.
Tyholland, Church of Ireland. © Jack Storey.