ไม่ต้องพูดน่ะ เลขนี้ดีสุดยอด 16/5/2562
Running West from Rock Creek Park along the Potomac River, the Chesapeake and Ohio (C&O) Canal lives on as a shining example of the American canal-building era. Engineering feats include the 11 stone aqueducts spanning major Potomac tributaries, the seven dams supplying water to the canal as well as 74 different canal locks to accommodate the elevation change of 605 feet.
from: http://ezinearticles.com/?Chesapeake-and-Ohio-Canal---19th-Century-Engineering-Feat-Transformed-Georgetown-Waterfront&id=6934187
