Indragupta

The last monk, known as Arhat Indragupta, after partaking the jackfruit, directed the merchants to a path which led to a cave with a silver ore. They informed the monach of their finding after arriving in Anuradhapura. He was much elated upon hearing the news. The ore provided the required amount of silver for the construction work.

In gratitude, he built a temple complex on the silver ore, employing 300 masons and 700 others including his chief artisan Vishwakarma Prathiraja.

Source

Wikipedia:Indragupta

https://en.wikipedia.org/wiki/Ridi_Viharaya