Blockchain is an emerging technology whose main characteristic is decentralized and distributed architecture with-out depending on a central server. Blockchain broadens the spectrum by providing a shared infrastructure that securely stores information and executes programs, making it a very disruptive technology. Because blockchain is a relatively novel technology, there is insufficient knowledge about architectural concerns for designing and evaluating blockchain-based solutions. In this paper, we report a systematic mapping study, giving a broader landscape of the blockchain-based architectural concerns, such as quality attributes, tactics, and patterns related to the architectural design space with blockchain. From the current literacy, this study unveils these concerns and their relationships. Software architects can use these concerns for analyzing, designing, assessing, or refactoring their blockchain-based solutions.