To cross a stream, road or valley (where the hold off because of a flight of locks at either side can be unacceptable) the valley could be spanned by a navigable aqueduct – a renowned example in Wales is the Pontcysyllte Aqueduct (now a UNESCO Globe Heritage Site) through https://canalinfantil22109.topbloghub.com/43503248/not-known-facts-about-canal-infantil