County Derry or County Londonderry on Wikipedia.

Aghadowey, St. Guaire (CoI). C 858 210. © Gerard Close.
Articlave, St. Paul (CoI, 1691). C 783 338. © Gerard Close (2013). Two interior views - 1, 2, and the sun-dial, the text of which reads "Tis greatly wise to talk with our past hours, and ask them what report they bore to Heaven." A plaque commemorates the re-dedication on the church's 300th anniversary. All © Adam McCurdy (2015). 1st Dunboe Presbyterian Church. C 781 340. © Gerard Close (2013).
Ardmore, St. Mary (R.C.). © Mark Lusby.

Ballerin, St. Mary (R.C.). C 805 198. © Gerard Close (2010).
Ballinderry, St. John (CoI). St. Patrick (R.C., 1843). H 934 811. Both © Gerard Close.
Ballygoney, Presbyterian Church. H 867 778. © Gerard Close (2012).
Ballyeglish, St. Matthias (CoI). H 894 841. © Gerard Close.
Ballykelly, Tamlaghfinlagan Parish Church (CoI). C 634 226. Presbyterian Church (1827). C 631 223. Both © Gerard Close (2010).
Ballylaggan, Reformed Presbyterian Church. H 881 249. © Gerard Close.
Ballylintagh, Gospel Hall. © Gerard Close.
Ballymaguigan, St. Trea (R.C). © Murray Lynn.
Ballywillan, Presbyterian Church. C 857 383. © Gerard Close.
Banagher (R.C.). © Mark Lusby. Presbyterian Church. C 610 057. © Gerard Close (2010).
Bellaghy.
Bellarena, St. Cadan (Tamlaghtard Parish Church). A glimpse of the interior, taken through a window. Both © Adam McCurdy (2015).
Bovevagh, Presbyterian Church. © Gerard Close. St. Eugenius (CoI). C 676 133. © Gerard Close (2010).

Castledawson, Presbyterian Church. H 925 932. The Aughrim Gospel Hall. H 927 904. Both © Gerard Close. St. Patrick (R.C.). © Gerard Close (2009). Christ Church (CoI). H 927 933. © Gerard Close (2010).
Castlerock, Christ Church (CoI, 1870). C 769 362. Presbyterian Church. C 776 357. Both © Gerard Close (2013).
Clady, St. Oliver Plunkett (R.C.). C958 035. © Gerard Close.
Claggan, Presbyterian Church, dating from 1846. J 782 848. © Gerard Close.
Coleraine.
Craigavole, St. Mary (R.C.). C 855 099. © Gerard Close.
Crossgar, Presbyterian Church. C 843 256. © Gerard Close.
Curran, Presbyterian Church (1936). H 890 951. © Gerard Close (2016).

Derry City.
Desertmartin, St. Mary (R.C.). H 849 928. Church of Ireland. H 855 929. Church of the Nazarene. H 853 923. The Lecumpher Presbyterian Church (1860). H857 893. All © Gerard Close.
Draperstown, Church of the Holy Rosary (R.C.). H 781 946. Presbyterian Church. H 783 946. St. Columba (CoI). H 782 947. All © Gerard Close.
Drumenagh, Gospel Hall. H 940 869. © Gerard Close (2016).
Drummullan, St. Joseph and St. Malachy (R.C.). H 861 788. © Gerard Close (2012).
Drumsurn.
Dungiven, St. Patrick (R.C.) on Chapel Road. C 694 085. © Gerard Close. Link. Parish Church (CoI). C 699 082. © Gerard Close (2010). Link. Presbyterian Church. C 688 095. © Gerard Close (2018).

Eglinton, St. Canice (CoI). C 523 202. St. Mary (R.C.). C 522 161. Faughanvale Presbyterian Church. C 535 203. All © Gerard Close (2010).

Garvagh, Main Street Presbyterian Church, founded 1773. The Presbyterian Church's motto "Ardens Sed Virens" - burning yet flourishing" is included on the church information board. St. Paul (CoI). C 839 159. Free Presbyterian Church. C 840 152. Mission Hall. C 840 157. All © Gerard Close. 1st Presbyterian Church (1641, re-built 1971). C 838 159. © Gerard Close (2010). Link.
Glen, St. Patrick (R.C., 1825, re-built 1911). C 930 008. © Gerard Close.
Glenullin, St. Joseph (R.C., 1885). C 816 138. © Gerard Close (2013).
Gorteade, Gospel Hall. C 875 046. © Gerard Close.

Keenaught, St. Patrick (R.C.). H 844 916. © Gerard Close (2011). The former St. Patrick (R.C.). H 824 923. © Gerard Close (2013).
Killykergan, Gospel Hall. C 847 197. © Gerard Close.
Kilrea.
Knockloughrim, The Termoneeny Parish Church (COI). H 894 968. Methodist Church. H 894 970. Both © Gerard Close (2010). Presbyterian Church (1840). H 890 978. © Gerard Close (2016).

Largy, Presbyterian Church (1831). C 673 183. © Gerard Close (2010).
Lavey, St. Mary (R.C.). This is the "new" church, dedicated in 1873. © Mark Lusby.
Limavady.
Lislea, the former Lislea Mission Hall (1926). C 950 074. © Gerard Close (2016).
Lissan, Church of Ireland. H 805 829. St. Michael (R.C., 1907). H 802 831. Both © Gerard Close.
Loughan, St. Paul (CoI). C 878 288. © Gerard Close (2011).

Macosquin, Presbyterian Church. C 844 270. © Gerard Close. St. Mary (CoI, 1827). C 825 288. © Gerard Close (2010).
Maghera, Presbyterian Church. C 851 002. Elim Pentecostal Church. C 850 003. St. Lurach (CoI). C 853 004. St. Mary (R.C.). C 851 005. All © Gerard Close. Chapel of Ease at the Anniscliffe House Care Home. C 854 013. © Gerard Close (2014).
Magherafelt.
Moneymore.
Moneyneena, St. Eugene (R.C). H 750 971. © Gerard Close (2010).

Newbuildings, Methodist Church (1853). C 412 125. © Gerard Close (2018). Link.

Portstewart, The Burnside Presbyterian Church. C 821 374. © Gerard Close. St. John the Baptist (CoI, 1841). C 816 381. © Gerard Close (2011). St. Mary Star of the Sea (R.C.). C 815 380. © Gerard Close (2011). Baptist Church. C 823 363. © Gerard Close (2013).

Quilly, Gospel Hall. H 858 867. © Gerard Close (2011).

Ringsend, Presbyterian Church. C 804 225. © Gerard Close.

Sixtowns, St. Patrick (R.C., 1854). H 724 903. © Gerard Close (2013).
Straw, St. Columba (R.C.). H 766 934. © Gerard Close (2010).
Swatragh, Presbyterian Church. C 859 079. St. John the Baptist (R.C.). C 853 073. Both © Gerard Close. Killeagh Parish Church (CoI). C 854 075. © Gerard Close (2011).

Tamlaght O'Crilly, St. Mary (R.C.) aka Drumagarner Chapel. Janice advises that it was built in 1778, burned and repaired in 1810, and more or less completely re-built in the mid 19th century. Interior view. Both © Janice Bacino. St. Nossonus (CoI). C 949 038. © Gerard Close (2011). Drimbolg Reformed Presbyterian Church. C 915 054. © Gerard Close (2011). Tamlaght O'Crilly Upper Parish Church (CoI). C 910 062. © Gerard Close (2011). Presbyterian Church. C 910 605. © Gerard Close (2011).
The Loup, Saltersland Presbyterian Church. St. Patrick (RC). H 903 844. Both © Gerard Close.
Tobermore, The Carson Memorial Baptist Church. Presbyterian Church. H 830 966. Church of Ireland. H 823 962. All © Gerard Close. Ruins of the church founded by St. Crunathan in the 6th century, though the present fabric is much later. H 816 950. © Gerard Close (2011).

Woodschapel, St. John (CoI). Gracefield Church (CoI, formerly Moravian, built 1769). H 938 893. Both © Gerard Close.