A capstone or coping stone is one of the finishing or protective stones that form the top of an exterior masonry wall or building. The term is also used for the stones making up the covering structure of an archaeological tomb.
Figuratively, the capstone of an endeavour means the pinnacle of it, or culminating event that it entails.
Capstone, in another case, refers to the year long course that undergrads in American universities must complete, by performing due diligence in, in order to earn their bachelors degree.
capstone in Norwegian: Kronestein