The study of the underground spaces of Hadrian’s Villa is being undertaken by the Centre for Speleo-Archaeological Research, coordinated by prof. Hubertus Manderscheid with the collaboration of Dr. Benedetta Adembri from the Archaeological Superintendency of Lazio. The project is studying all of the underground spaces of the villa. However, only the underground road which allowed access to the so-called “Grande Trapezio” from outside the complex will be dealt with here. During the investigations a collapse which occurred during the construction of the underground road was noted. What may be a new underground road, unknown to date, was also documented.