Badia di S. Sebastiano, Medieval abbey in Alatri, Italy.

Badia di S. Sebastiano is a Benedictine monastery built on a hilltop east of Alatri's center with medieval architectural features throughout its complex. The site is now divided into three sections, and the church preserves frescoes and other original medieval elements from centuries past.

The monastery was founded in the early 6th century and later received a visit that linked it to the broader monastic movement of that era. This connection to early monasticism established its role as part of an important religious network in the region.

The church displays wall paintings from the 13th century showing scenes from the lives of Christ and the Madonna, reflecting the artistic traditions of schools from the surrounding regions. These frescoes remain visible to visitors and reveal how religious art was created and valued in medieval times.

The site is reachable via Via Collemassaro and maintains its original layout divided into three distinct sections. Wear sturdy shoes for walking the hilly terrain, and note that some areas may have limited access depending on current conditions.

Around 528 Benedict of Nursia stopped here on his way to Montecassino and gave Abbot Servando a small bell in thanks for the hospitality. That bell is kept today in the Monastery of the Benedictine Sisters of Alatri, not at the abbey itself.