Poppi rises on a hill dominating the Arno river in the Casentino Valley. The seat of the Count Guidi family who ruled the valley from the early 1000s until 1289 when they finally became part of the Florentine Republic. From the late 1200s to 1448 the Guidi family presided in the Palazzo dei Guidi and controlled the land from Poppi to the mountain pass of the Consuma.
Approaching the Campaldino plain, the tall and imposing thirteenth-century castle of the Guidi Counts on the hilltop of Poppi dominates the surrounding countryside. The Castle is characterised by a facade with double-arched windows and the tall tower rising from the centre.
The late-thirteenth-century Badia di S. Fedele in the old town centre of Poppi houses many precious paintings, while to the north of the town lies the 10th-century Abbey of Strumi. Legend holds that the Antipope Calixtus III, set up by Frederick Barbarossa, originated from Strumi. Also worth visiting in the town are the churches of S. Giacomo a Moggiona and S. Bartolomeo ad Agna.