Bishop Archibald enlarged or rebuilt the castle in c. 1280 and it continued to be used by the bishops until the late 14th century. Nothing now exists of the castle except one fragment of a rubble wall that is integrated into the Kinneddar kirkyard boundary wall. Loch Spynie, then open to the sea and much larger than its present size, came close to the castle and its marshes surrounded the castle enclosure on three sides. The ruinous structure still existed in 1734 and was described as being a central tower enclosed by two concentric hexagonal walls which made it unique in Scottish terms.
Adjacent to the castle grounds stood the ancient kirk of Kinneddar which became the second cathedral of Moray following the move of the bishop's seat from Birnie. The Pictish sculptures found in the vicinity of the castle and kirkyard point to the area being an important 8th century Christian centre (see Culdees) and may have been a principal location for the conversion of the Picts.
- Royal Commission on the ancient and Historical Monuments of Scotland, Archaeological Notes: Canmore ID 16459
- Cramond, Records of Elgin, pp. 16–7. Cramond cites the primary source, the Registry of Moray where Bishop Bur arrests a ship on 7 June 1383 in the tidal Loch Spynie delivering cargo to the burgesses of Elgin. Bur was sailing from his residence at Kinneddar Castle to the church of Urquhart.
- Oram, Moray & Badenoch, p. 122
- Oram, Moray & Badenoch, p. 98
- Cramond, William (1908). The Records of Elgin. Aberdeen: New Spalding Club.
- Oram, Richard (1996). Moray & Badenoch, A Historical Guide. Edinburgh: Birlinn. ISBN 1-874744-46-7.
- "Kinneddar, Bishops Palace". Archaeological Notes, Canmore ID: 16459. Royal Commission on the ancient and Historical Monuments of Scotland. Retrieved 12 April 2010.