<p>The Holy Crown of Hungary is a unique medieval artefact whose debated origin is examined through an archaeoengineering approach specifically developed for its objective, scientific investigation. Within this methodological framework, the technology revealed by dimensional and visual investigation is integrated with the study of the Crown’s international enamelling tradition. The hypothesised manufacturing process was validated through the construction of a full-scale replica, while Failure Mode and Effects Analysis (FMEA) provided a systematic means of excluding alternative assembly hypotheses. Rather than functioning as a supplementary aid, engineering-based reasoning plays a central role in determining the artefact’s chronology and technological coherence. The study establishes archaeoengineering as a rigorous and transferable framework within heritage science, capable of producing reproducible results and applicable across other culturally significant artefacts.</p>