Software engineers must ensure that systems under development are endowed with software architectures that enable them to meet their requirements. Apart from functionality, systems also have to satisfy extra-functional requirements that may include behavioural constraints that the software must adhere to, as well as qualities to optimise like performance, availability, and energy efficiency. These qualities are often inter-dependent and heavily influenced by the structure of the system. This results in poorly understood multi-dimensional design spaces, in which trade-offs among qualities are not evident when making architectural decisions. This paper presents Voyager, a tool which allows engineers to visualise architectural configurations and explore the trade-offs among their quality attributes in a multi-dimensional design space. The tool produces contextual visualisations to facilitate trade-off analysis, providing engineers with a streamlined way of understanding architectural design spaces, using an approach that combines architectural structure with multi-dimensional data visualisations. A user study was conducted to evaluate the effectiveness of the tool. Results show that participants achieved a significantly higher accuracy in a shorter time span and had a better user experience when using Voyager, with respect to an existing comparable tool.