Beautiful and practical, Corten steel is an excellent material.

Corten is a weathering steel. This material is a corrosion resistant steel, that left uncoated develops an outer layer patina. This patina protects the steel from additional corrosion. Instead of ruining the metal, rust actually serves to protect Corten from further corrosion. 

Objects built with Corten steel take on the reddish, orange color of rust. As the rust deepens with further exposure to the environment, the steel develops a deep russet patina that many people find appealing.