Nirayama Reverberatory Furnaces are located in Izunokuni, Shizuoka prefecture. It is the only remaining reverberatory furnace in Japan and are listed on UNESCO World Heritage since 2015.
Reverberatory furnace is "a metallurgical or process furnace that isolates the material being processed from contact with the fuel, but not from contact with combustion gases. It was needed for smelting metals, such as iron,copper and bronze from 18th to 19th century.
Tokugawa shogunate decided to build the reverberatory furnace in 1853. The decision was brought due to the First Opium war in 1840 and Perry Expedition in 1853. Japan did not want to be invaded, therefore she had to be armed. The furnace was built in 1857.
To be armed, the shogunate needed cannons to protect the city of Edo(current Tokyo). At that time, cannons could be bought from the United States, Great Britain, France and etc. in 19th century but it will take time to import and of course expensive to buy all the time. Therefore the reververatory furnances were needed.
How to get here: Take Tokaido Shinkansen to Mishima and change there to Izuhakone railway Sunzu line to Izu-Nagaoka station. Then, take a bus. Also, you can take limited express Izu-no-odoriko bound for Shuzenji to Izu-Nagaoka station. Please aware that Japan Rail Pass is not valid on Izuhakone railway.