Accessing historical price data for cryptocurrencies is crucial for Web3 applications, particularly for DeFi protocols that require secure, accurate, and trustworthy information. Chainlink Price Feeds, a widely used decentralized oracle in the DeFi ecosystem, provides such data by aggregating inputs from multiple providers, ensuring reliability and decentralization. While obtaining current price data is straightforward, retrieving historical data involves complexities such as navigating different aggregator contract versions and determining the correct round ID. Chainlink's solution involves using a decentralized oracle network to perform off-chain calculations, thus minimizing trust requirements and avoiding the need to store large amounts of data on-chain. This method allows smart contracts to access verifiable historical price data securely, using external adapters that calculate and return round IDs, which can then be confirmed on-chain, mitigating the risks associated with centralized data sources.