Madinat al-Zahra, an iconic 10th-century city constructed under Abd al-Rahman III, symbolized the power and prestige of the Umayyad Caliphate in al-Andalus. Despite its partial destruction in the 11th century, key architectural elements have survived. Only about 10% of the site area has been excavated, mainly the palace core. Among the discovered remains, the Great Portico stands out as a key ceremonial gateway to the palace complex. Originally featuring a fourteen-arch arcade and partially reconstructed in the mid‑1970s/1980s, the monument today lacks thorough documentation of the interventions performed, which limits understanding of its current configuration and complicates future conservation efforts. The present document describes the preliminary phase of a study aiming to assess the materials and mechanical properties of the Great Portico, distinguishing between original and reconstructed sections, for which non-destructive techniques, including ultrasonic and Schmidt Hammer testing, were employed. A preliminary map integrating these findings supports structural modelling and heritage management. Understanding the structural behaviour of Medina Azahara’s arches contributes not only to its preservation but also to the broader conservation of historic Islamic architecture in Spain. The study highlights the importance of safeguarding this UNESCO World Heritage Site while providing insights applicable to similar architectural heritage structures.