"a Doric temple stood by the water's edge"
Dunstall Castle Folly, Worcestershire
Creative Commons Attribution Share AlikeDunstall Castle Folly, Worcestershire - Credit: Bob Embleton, Wikimedia Commons

This type of building is known as a folly.

A folly is a building placed in a garden or landscape purely for the purpose of decoration and amusement.

Follies were particularly popular during the 18th Century, and were often constructed in imitation of buildings such as classical temples, Chinese temples, Egyptian pyramids, towers, ruined abbeys or castles, rustic villages or mills.

Doric is the term for the earliest and simplest form of Ancient Greek architecture, characterised by baseless fluted columns finished with a flat slab of stone.

 

Doric Temple, Petworth House
Creative Commons Attribution Share AlikeDoric Temple, Petworth House - Credit: Andy Potter, Wikimedia Commons