Thangtong Gyalpo (1385-1464) was a great Buddhist, and famously known as ChakZampa (iron bridge builder) is said to have built many iron chain suspension bridges around Tibet and Bhutan, several of which we can still see today.
one of which we come across is, as you drive through Thimphu-Paro high way. the Famous Tachog Lhakhang overlooking Pachu just between Isuna and ChuZom. it is a must visit place and if you ever travel to Paro to Thimphu, it worth visiting there. it happens to me and had a great day