[4] We are confirmed in that view also by the fact that Regulation No.16 (above quoted) made it unlawful for any person or persons to erect any fence, wharf, boat house, building or other structure whatsoever to seaward of the public highway or road running along high-water mark of the Harbor of Pago Pago being Number 15 of 1900 without special permission from the Commandant of the United States