To cross a stream, highway or valley (wherever the delay brought on by a flight of locks at either facet might be unacceptable) the valley is often spanned by a navigable aqueduct – a popular illustration in Wales could be the Pontcysyllte Aqueduct (now a UNESCO Entire world Heritage https://musica-infantil88776.ssnblog.com/36073600/little-known-facts-about-musica-infantil