This study focuses on the vibration and modal analysis of the Roman Walls of Lugo, a UNESCO World Heritage Site known for its historical and architectural significance. The wall is one of the most important structures of Hispania Romana, since it is the

only fortification which has preserved its entire perimeter and it is the only one on the peninsula possessing a maintenance plan. The research involved vibration tests and modal identification in three areas of the walls: Porta San Fernando, Porta Bispo Odoario, and Porta San Pedro. The aim was to assess the dynamic behavior of the structure, analyze vibration levels, and identify low-frequency vibration modes across the different measurement zones.

Triaxial and uniaxial acceleration sensors were placed at various points, including the base and upper sections of the wall. Data were collected at a sampling frequency of 50 Hz, enabling the determination of natural frequencies, acceleration amplitudes, and vibration transmission characteristics. Modal analysis revealed consistent low-frequency modes across the studied sections, providing valuable insights into the structural response.

The results indicated that, despite vibrations caused by external factors such as vehicular traffic, the measured levels remain within acceptable thresholds as defined by international standards. These findings affirm the structural integrity of the walls and highlight the importance of vibration and modal monitoring in the preservation of historical structures, particularly those exposed to urban and environmental influences