To cross a stream, street or valley (wherever the hold off because of a flight of locks at possibly aspect can be unacceptable) the valley is often spanned by a navigable aqueduct – a well known illustration in Wales could be the Pontcysyllte Aqueduct (now a UNESCO World Heritage https://andyszfls.mybuzzblog.com/17000362/5-easy-facts-about-musica-infantil-described