Comprehending large-scale software systems is a challenging and daunting task, particularly when only source code is available. While software visualization attempts to aid that process, existing tools primarily visualize a system's structure in terms of files, folders, packages, or namespaces, neglecting its logical decomposition into cohesive architectural components.We present the tool Immersive Software Archaeology (ISA) which (i) estimates a view of a system's architecture by utilizing concepts from software architecture recovery and (ii) visualizes the results in virtual reality (VR) so that users can explore a subject system interactively, making the process more engaging. In VR, a semantic zoom lets users gradually transition between architectural components of different granularity and classlevel elements while relationship graphs let users navigate along connections across classes and architectural components.We present results from a controlled experiment with 54 participants to investigate the usefulness of ISA for assisting engineers with exploring an unfamiliar large-scale system compared to another state-of-the-art VR approach and an IDE.