What chain is Celo on?

Could you please elaborate on the blockchain technology that Celo utilizes? I'm curious to understand the underlying infrastructure that powers this innovative cryptocurrency platform. Specifically, I'm wondering if Celo is built on a well-known blockchain like Ethereum, or if it has a unique, proprietary blockchain design. Your insights would greatly help me in gaining a deeper understanding of Celo's technological foundations and how it compares to other cryptocurrencies in the market. Thank you for your time and expertise in this matter.