Is Celo built on Ethereum?

Could you elaborate on the relationship between Celo and Ethereum? Is Celo indeed built on the Ethereum blockchain? If so, how does this influence its functionality and capabilities? Does it leverage Ethereum's smart contract functionality? Or does it utilize other components of the Ethereum ecosystem? I'm particularly interested in understanding the technical details behind this integration, if any, and how it shapes the overall architecture and performance of the Celo network. Additionally, what are the benefits and limitations of this approach?