broch

plural brochs

1. archaeologyA type of Iron Age stone tower with hollow double-layered walls found on Orkney, Shetland, in the Hebrides and parts of the Scottish mainland.

   The last man slid the bolt in the single low narrow door. The broch was impregnable then.

   1972, George Mackay Brown, Greenvoe, Polygon, published 2019, page 20

   2 more examples

   Finella's carles builded the Kaimes, a long line of battlements under the hills, midway a tower that was older still, a broch from the days of the Pictish men […].

   1933, Lewis Grassic Gibbon, Cloud Howe (A Scots Quair), Polygon, published 2006, page 268

   Ian's eyes rolled slowly up, as though following the rough stones of the broch upwards. 'That tower rises sixty feet from the ground,' he told me, 'and it's thirty feet in diameter, wi' three floors.'

   1991, Diana Gabaldon, chapter 29, in Outlander, London: Random House

   Synonyms: Pictish tower