The patron saint of Macchia d'Isernia is Saint Nicholas of Bari, celebrated on 9 May, in the church dedicated to him in the heart of the village: it dates from the 14th century, originally consecrated to Saint Blaise, but extensively restored in the 18th century thanks to the barons d'Alena and the bishop of Isernia, who in 1780 rededicated it to Saint Nicholas of Bari in honour of Nicola d'Alena, the town's first feudal lord and founder of the family of the same name. The building preserves a Baroque portal with a broken curved pediment and a medieval turreted bell tower with arrow slits.
The town also preserves the baronial castle of the d'Alena family, built around 1100 by Clementina, daughter of Roger II of Sicily, when the fief was part of the county of Ugo of Molise: passed over time to the Anjou, the Afflitto and the barons Rotondi, it was restored in Renaissance style in 1480 as a patrician residence. The town's name recalls its origins in the 10th century, linked to an ancient «Maccla Saracina» that already existed in Samnite times.
