Castle Sinclair is a spectacular cliff top ruin about four kilometres from the Town of Wick. It has its own website, so there's no point in me describing it in detail here.
When I visited in June 2010 it was unfortunately closed to the public for repairs to stabilize the structure, and one of the walls was obscured by scaffolding. It was still well worth seeing, and I was happy with my exterior photographs. I thought the overcast sky and grey sea created a dramatic backdrop.