The Erection

I was surfing the web and thought of checking "why a building is called a building and not a "built" or something ?!". And I found a very funny answer on a forum which said "Why not call it an "erect" ?" .People would be seen saying "I just moved to a new erection !". Rotflmao. Wonder how this originated ? Maybe...the first building was never completed, maybe it went on for years and years which lead to the present continuous verb for it.