During the laying of a pavement and a loose stone foundation inside the small church of S. Bartolomeo al Bosco a brief archaeological investigation was carried out.
The present church, so named as it stands in the centre of a clearing in the woods surrounding Appiano Gentile, is the result of the transformation, at the end of the 16th century, of a larger Romanesque structure (first half of the 12th century). This structure originally had three naves with an apse orientated to the south-east and a wide façade orientated towards the north-west and divided into three sections. The transformation created a small structure with a single nave, a rectangular apse and a new façade with a single arch opening in the north-east wall.
The removal of the two latest pavements revealed, below layers of silt containing a substantial amount of rubble (first half of last century) and clayey silt, column and pilaster bases. Imposing columns in sarizzo must have stood on these bases, which, with their fogliate capitals were still visible at the end of the 16th century and are in part conserved in dwellings annexed to the church.
The plan of 1596, made following the pastoral visit of Antonio Albergato, representative of Cardinal Federico Borromeo, provides one of the last representations of the church’s development. It is shown divided into three naves, with an apse and two semicircular chapels with altars, opening off of the side walls.
At the end of the 16th century the church was in ruins and following the pastoral visit it was reduced in size. It has always been associated with the presence of the so-called “urn of Walpert”, which was housed here until 1884 (today it can be seen in the cloister of the Civico Museo Archaeologico, Milan). Interest for this object is linked both to its provenance, its primary function in the Roman period and the subsequent reuse that Walpert, a priest from the diocese of Milan, made of it sometime between the 9th and 11th century. (Stefania Jorio, Chiara Niccoli)