The word capital comes from the Latin word caput,which means head and, by extension, important.(Most of us would agree that our heads are very important to us.)
Like many other Latin words, caput has quite a few English "descendants." In government, there arecapital cities and capitol buildings, important places where the heads of government meet. In architecture, there are Doric, Ionic, and Corinthian capitals that decorate the tops of columns (where their heads would be, if columns had heads!).