Tachogang Lhakhang was built by Tangtong Gyelpo in the fifteenth century. The temple was likely constructed in 1420. While the Tibetan master was meditating here, he had a vision of an emanation of Avalokiteshvara and decided to built a temple as well as an iron suspension bridge at this location. Tachogang lies on the way from Paro to the capital Thimpu. A new temple at Tachogang was built in the seventeenth century by the Fourth Druk Desi Tendzin Rabgye, as the original was destroyed after it served as the main seat for the Five Groups of Lamas, a coalition of local leaders who had opposed the Zhabdrung Ngawang Namgyel.


I found it amazing that this 15th century iron had not rusted!

https://treasuryoflives.org/institution/Tachogang-Lhakhang