To cross a stream, street or valley (the place the delay because of a flight of locks at possibly facet might be unacceptable) the valley is often spanned by a navigable aqueduct – a famed case in point in Wales could be the Pontcysyllte Aqueduct (now a UNESCO Planet https://travisfcvph.bloginwi.com/70740188/considerations-to-know-about-canal-infantil