To cross a stream, street or valley (in which the delay caused by a flight of locks at possibly facet can be unacceptable) the valley is often spanned by a navigable aqueduct – a popular instance in Wales will be the Pontcysyllte Aqueduct (now a UNESCO World Heritage Web https://milooxbfl.designi1.com/57944745/5-easy-facts-about-musica-infantil-described