Major alignments
The most intriguing alignment in Orkney I have found so far is the one that runs from the vertical cliff faces of Hoy to the caves of Gentleman’s Ha on Westray island.
Starting from Westray the alignment passes over several hilltops, then over the islet of Wart Holm, the headlands of Faraclett (little lake) and Aikerness, over the Hill of Huntis, the Kame of Corrigal, (and Corrigal Farm!), a waterfall near Stromness, and eventually the dramatically ravaged Kame of Hoy with at the back the thousand feet high vertical cliff face of St John’s Head, the highest in Britain; actually an enormous sea stack in the making.
This alignment of resilient rock has an astounding 9 or more megalithic buildings on one line, these are among the more important of Orkney, including from the south, the Ring of Bookan, Hainger Howe, close by War Memorial Harray (most probably a hidden chamber), Corrigal Farm (whatever it was before), Reeky Knowes, Knowe of Ramsay (or Lairo, two maps differ here) and three chambers near Rinyo, on Faraclett head, of which the highest up has a twin cairn nearby.
There are several of these alignments stretching over two or more islands, that is over 50 km with a theoretical width of about 50m, often much less.
Another alignment of great importance and seemingly over a broader band is the one that starts on the fault line at Waulkmill Bay, then passes over the top of South Rusky Hill, the water hill with moving sprins, continues exactly parallel to the road of Bigswell, passes near Stones of Stenness, runs through the Ring of Brodgar, passes near the Ring of Bookan and continues to Skara Brae and the natural arch Hole o’Row.
Exactly parallel to this line is the one that aligns the centres of Stenness and Bookan (and maybe with the holy well at Bigswell)
The next amazing one is from the Stack of Yesnaby, Burn of Woodwick (faultline?), Chapel Wyre (former chamber), Chamber Egilsay (MH-type), near Flaughton Hill top (Eday) and eventually the huge chamber of Quoyness (MH) on Sanday
On Eday is the alignment parallel to the boundary of Eday beds and Rousay Flags. Here a line from Ward Hill, south Eday, to Grey Head (natural arch), north on the Calf, has at least 3 chambers and 3 quarries along with 5 hill tops aligned, very impressive and convincing.