Located along the current Via Lazzaretto, the Church of San Lazzaro is one of Trecella’s oldest historical landmarks. Surrounded by a garden that once housed the community’s cemetery, it stands as a significant reference point in local history, weaving together religious tradition, architectural transformations and the memory of past epidemic events.

According to tradition, the site where the church stands sheltered three friars fleeing the Burgundians’ persecution during the siege of Milan. The construction of the building dates back to the 9th century, but its first documentary evidence appears in the 13th century, when the church is listed as part of the Pieve of Gorgonzola in Liber Notitiae Sanctorum Mediolani. The dedication to Saint Lazarus refers to the biblical figure of the beggar mentioned in the parable of poor Lazarus and the rich man.

In 1288, two churches were recorded in Trecella: San Lazzaro and San Marco and Gregorio.

The single-nave Church of San Lazzaro has a small sacristy with an upper floor, once used as clergy residence. In the centre of the nave, there is a square stone leading to the ossuary.

Over the centuries, the building underwent several structural interventions: in the 16th century, structural consolidation works were carried out, and a small window was built on the south side. The church was also turned into a lazaret during epidemics, particularly during the 1576 plague of Saint Charles and the 1918-1920 Spanish flu pandemic. San Lazzaroo was Trecella’s parish church until 1558 when, due to its poor condition, all religious services were suspended in it and moved to the Church of San Marco and Gregorio, located in today’s Piazza San Marco, on the present site of the “bar della Cooperativa”.

Inside the church, above the altar, there is the original painting from the votive chapel of San Rocco which replaced a statue of Christ now preserved in the parish church of San Marco. Also remarkable is the 16th-century marble tabernacle originally located inside the Church of San Lazzaro and then placed above the entrance portal. During a pastoral visit, Cardinal Schuster judged this location inadequate and recommended moving the tabernacle to the parish church of San Marco, where it can still be admired. A similar tabernacle can be seen in the Church of San Maurizio al Monastero Maggiore in Milan.

The upper floor of the building provides access to the small bell tower, with a bell rope still in place.

Although no longer a site for regular worship, the Church of San Lazzaro still serves a liturgical function, being open for special occasions and private celebrations, such as weddings. Outside the building, slightly raised above the street level, is the ancient cemetery which was used until the late 18th century. To commemorate its function, a memorial stone topped with an iron cross bears the inscription: «HERE LIE OUR BELOVED ONES 1400-1800».

Thus, the Church of San Lazzaro stands as a precious witness to the religious and social history of the area, a place of collective memory and identity heritage for the community of Trecella.