Mainland on Wikipedia.
 

Birsay, St. Magnus. HY 2476 2770. © Peter Morgan (2021). Some O.S. maps also have a label for Christ Kirk (Site of) indicating the present church, with a dotted line for an apse at the east end. More on this on Wikipedia, where it suggests that it was perhaps the site of Orkney's first cathedral.
Brough of Deerness, remains of the medieval chapel. HY 597 088. © Martin Briscoe.

Deerness, St. Ninian (CoS). © Peter Amsden (2012). Grade B listed - link.
Dounby, United Free Church. HY 296 206. © Martin Briscoe.

Evie, the Parish Church. HY 368 256. Trevor Hunt, the Minister, has advised that this church was sold in 2004 (for conversion to a residence) and the congregation has been meeting in a local school since then. They will be moving into a newly built church (© Trevor Hunt) soon - the dedication ceremony is planned for June 10, 2007. HY 268 254. The Old Parish Church. HY 375 247. First and third photos © Martin Briscoe.

Finstown, Firth Church (CoS). HY 360 138. The former Free Church, recently converted into holiday accommodation. HY 360 139. Both © Martin Briscoe. Another view (in 2007). © Trevor Hunt. The former Firth Paterson United Presbyterian Church (now a shop) was built towards the end of the 19th century, replacing an earlier building, originally erected in 1837 as the Secession Mission Station. © Trevor Hunt.

Gorseness, ruined church. HY 424 197. © Martin Briscoe.

Hackland. HY 393 206. © Martin Briscoe.
Harray.
Holm. Holm Church is now known as the East Mainland Church (CoS), the congregations of Deerness, Holm, and St. Andrew (at Tankerness) having united a few years ago. Deerness Church is being sold, as is St. Andrew. HY 504 019. © Martin Briscoe.
Howes Wick, Old Parish Church. HY 511 007. © Martin Briscoe.

Kirkwall.

Orphir, the remains of St. Nicholas. The only circular church known to have been built in medieval Scotland. HY 335 044. © Martin Briscoe.

Queenamuckle. HY 415 216. © Martin Briscoe.
Quoyloo, the former Sandwick Parish Church, which Kevin Price advises was sold in 2008. HY 24546 2075. © Martin Briscoe. St. Peter's Kirk. Kevin advises that this is also now closed, and cared for by the Scottish Redundant Churches Trust. HY 2347 1987. © Martin Briscoe. Another view, and the interior, both © Peter Morgan (2021).

Skaill, St. Ninian. HY 588 064. West Church. HY 572 062. Both © Martin Briscoe. Kevin Price advises (2011) that St. Ninian is now in Community use, and that West Church has been converted into a house.
Stenness, Church of Scotland. Its grade C listing dates it to circa 1910, on the site of an earlier church. HY 3107 1245. © Martin Briscoe. Another view, © Peter Morgan (2021). Link.
Stromness.

Tankerness, St. Andrew's North Church. HY 511 080. St. Andrew's South Church. HY 511 068. Both © Martin Briscoe. Kevin Price advises (2011) that both churches are now closed, and that South Church has been converted into a house.
Twatt. © Martin Briscoe. Kevin Price advises (2011) that the church was sold in 2008. A new church is being built in Dounby, which will be Milestone Community Church, and will serve the parishes of Birsay, Harray and Sandwick.