Straight - to the Points

Our U3A group has set the challenge to take images where the predominant lines are all straight or all curved.
Guess which this is?

The wooden framework is all that is left of what I assume to have been a light or beacon at the harbour entrace at Limekilns/Charlestown (Fife). The view is to the west and three cranes on the jetty at Defence Munitions, Crombie.