The stairway

Description:
The spaces immediately outside the tower n. 1 and the two stretches of wall that lean on it, consisting of beds of rock subject to anthropogenic changes and a layer of collapse, the composition and proportion is different from the remainder covering general collapse the entire area of excavation. The first bench of rock (US 19) placed at the North-East boundary of the  area, is cut regularly, sloping down from above (corresponding to the above Tower  n. 1, of the twelfth century) down and has a rectangular shape; the clear cuts that are aimed to characterize the foundation of a high masonry. This part of the bedrock is free ( has no overlapped structures) on the north side of the leaning tower, while  leans against the south wall  (US 10) on which they opened the door to the complex "forecastle "(XIII century).
A second bench of rock (US 20), far from the first about 3 meters, has developed east-west "to rise" in the direction of the tower and worked through the excavation of cuts (US 21, US 22, US. 23) functional to the slope (in exemple constitute steps).
This space was covered with a layer of collapse (US 18), which for its characteristics and the altimetry (more elevated) differed significantly from the near collapse (US 4) extended over the entire Area 2. The two collapsed layers were in fact separated by a strip in which stones were not present, the collapse  US 18 was also rectangular, narrow and elongated, composed of stones of small to medium size.
Finally be pointed out two additional factors: the presence of two stone slabs overlapping each other at the southern angle of the Tower n. 1 and the presence of at least five other similar slabs collapsed and located between the empty space that separates the two collapses (US 18 and US 4) and the same general collapse covering the entire area of excavation (US 4).

Interpretation:
The sample of indicators described are the evidence of a planted type masonry stairway that ran on the south side of the tower, giving it access, with an invitation relased immediatly over  the bench of rock (US 20) on which were carved some steps ( US 21, US 22, US 23).
The collapse of US 18 is the collapse of the masonry structure that housed the steps of the staircase (maybe a ramp), and this was based largely on the bench stone (US 20). The steps (two still in place) were made of rectangular slabs of stone, with a thickness of about 20 cm and measures 1,30 meters.
The structure was present in Phase I of the castle and it is dated to the twelfth century (the first certificate on written source dates from 1117, when the "Castellione" was donated by the counts of Sarteano, the Manenti family, to the Abbey of San Piero in Campo in Val d 'Orcia). Even in later phases (Phase 2 and 3), the staircase seems to be used to gain access to the Tower n. 1, with the new curtain wall (US 10) built during the thirteenth century that support them: not coincidentally the most raised rock bench ( U.S. 19) is reached by the defensive wall on its lower side and does not connect directly to the tower.
The staircase of masonry had to have a shape, though smaller, similar to thatlocatde outside Palatium Montarrenti (Sovicille - SI). 

Reconstructive hypothesis:
The draw shown in the photogallery reproduces the staircase view from the corner south-west of the Area 2.
Reconstruction is based on the actual layout of the wall remains unearthed in the excavation.
In high contrast, the design is the result of reconstructive hypothesis that takes inspiration from the archaeological and iconographic data from other contexts (see page "reconstructive hypothesis").