monument
Decorative or symbolic structures which generally have some referential meaning for the local place or population.
A monument is a structure which is built to decorate the landscape, to memorialize something or someone, or to represent something of particular importance. The shape of a monument may vary considerably depending on its specific structural form, and certain categories (such as sculptures) can take virtually any buildable form that does not clearly place it in another category.
The purpose can be decorative, commemorative, or representational. It does not require one particular shape or a uniform method of construction.
A permanent outdoor artwork and a water feature can both decorate a place or carry commemorative meaning. Each gives that purpose a different physical form.