The Calstock Viaduct was built between 1904 to 1907.  It carries a single track. railroad line over the Tamar River. It is the largest viaduct in Britain built with concrete blocks.  11,148 precast concrete blocks were used.

     The structure is 120 feet tall and 800 feet long.It consists of 12  60 foot 

.spans

     The viaduct was designed John Lang, Richard Chris, and William Gooch Rave.