This is the lighthouse at la Pointe d'Aigle which, together with a number of buoys, marks and delineates the entrance from St. Brieuc bay to the inland port of Legué in northern Brittany - the channel is very narrow and would otherwise be very difficult to navigate.
The granite causeway was constructed in 1855 and the lighthouse itself was finished in 1857. The light was commissioned 1 April 1857 with a fixed white light provided by an oil lamp. The light was converted to electric power in 1925 with a fixed green light. Finally, in September 2014 the light was converted to a green flashing LED which is visible from 8 nautical miles away.
The light also serves as a day-mark and to make it more easily visible, the north-east sea facing side of the tower is painted white - you can just see the beginning of the white band on the left side of the tower in this picture.
This was taken at low-tide and the sea is about 1 km away, but you can see the high-tide line quite clearly.
Stunning Richard, in this brief time I have viewed your work it is intriguing and gives the feel of true craftsmanship to the photographs. You inspire me to add France to my bucket list of places to photograph.
