The fortified site of Castel di Mura or Castrum de Muris is situated on the summit of Monte Castello (827 m a.s.l.), in the Apennines near Pistoia, close to the Apennine ridge. It lies a short distance from the village of Lizzano (San Marcello Piteglio), where a curtis is documented in the 10th century, and the earlier parish church of the Montagna di Pistoia was also situated.
Castel di Mura was part of the Apennine ridge defensive system, linked to routes leading to Florence, Pistoia, Lucca, Modena and Bologna, formed by the ‘Torri di Popiglio’ (Fortezza della Sicurana), the ‘Torre del Partitoio’ and other fortified sites, reorganised by the Municipality of Pistoia in the 1330s. Moreover, at least between 1358 and 1361, it was the seat of the ‘Captain of the Mountain’. Prior to these excavations (begun in 2017), the site was known through field surveys, archive research and reports of finds.

The excavations have concentrated on a number of areas on the summit of Monte Castello, where both field survey and georadar survey have revealed the presence of structures.
The first campaign (2017) analysed the phases of abandonment and agricultural use in more recent centuries and the residential and military phases of the 14th and 15th centuries. The base of a tower was exposed, with a room abutting it externally, which links it to a polygonal enclosure that had a turret and cistern. A probable gate was also identified; open in the south-eastern section of an external curtain wall, identified in several places, along the summit’s profile. The gate was situated in correspondence with the steepest part of Monte Castello, an impracticable zone, probably altered by landslides that could have caused the partial destruction of the gate of which only one jamb and part of the threshold were preserved.
Oral sources recall the existence of an entrance in this position. The memories are linked to the celebration of a procession on the occasion of the feast of the Assumption, which reached the summit of Monte Castello at the south-eastern edge.

The excavations excluded the existence of a second gate, also recalled by oral sources, at the north-eastern corner where the present access point to the summit is situated.