No courthouse or county site shall be removed except by a majority vote of the qualified electors of said county, voting at an election held for such purpose, and when an election has once been held no other election shall be held for such purpose until the expiration of four years; provided, that the county site of Shelby county shall remain at Columbiana, unless removed by a vote of the people, as provided for in an act entitled, "An act to provide for the permanent location of the county site of Shelby county, Alabama, by a vote of the qualified electors of said county," approved the 9th day of February, 1899, and the act amendatory thereof, approved the 20th day of February, 1899, or by an election held under the provisions of this article.