All other comments on this site about "ornate", "quirky", and "elaborate" lighthouse designs pale into insignificance beside this example.  This is Kronborg Castle, also known as Helsingør Castle or, if you are in a particularly Shakespearean frame of mind, Elsinore Castle situated at the narrowest point of the Øresund, the strait separating Denmark from Sweden.  The castle itself was built in around 1585 (although there was an earlier fortification on the site from the 1420s) to guard the entrance, via the Øresund, to the Baltic sea.  The castle, of course, formed the basis for the setting of Shakespeare's play "The Tragical History of Hamlet, Prince of Denmark" - or just "Hamlet" if you happen to be on friendly terms.  The history of the light is somewhat complex - a light, to assist shipping, was first displayed in a window of the tower (known as the Queen's Tower) in 1772, and a lantern was added to the tower in 1800.  The first fresnel lens in service in Denmark was installed in the lantern in 1842, but the present lantern dates "only" from 1878. 

The photo below gives an overview of the castle with the light visible on the closest corner tower - and how's that for a keepers' cottage?!!!