Casciana Alta was once an important castle called Sessana, of which there were two parts: the one around the fortress (whose layout has been preserved) and the one further down (called Croce). In the village is the Church of San Nicola, which preserves interesting works by 16th-17th-century Tuscan artists. It also housed the polyptych of a Virgin and Child from Pisa Cathedral, now in the Museo Nazionale di San Matteo, also in Pisa. Just outside the village is the Church of San Niccolò a Sessana, a former Marian oratory that still retains parts in Romanesque style. The single-nave interior with transept and three apsidal chapels has five altars: two are by the school of Santi di Tito, one depicts the Circumcision of Christ, and one the Madonna of the Rosary with St Dominic and St Catherine.
However, the most interesting religious building is located outside the town: the Oratory of the Madonna della Cava, one of the few octagonal buildings in Tuscany. There are various versions on its origin, the most accredited of which reports that in that place there was a shrine with a fresco of a Madonna and Child (called Madonna della Cava) by an unknown author. As a result of the many miracles attributed to her by the population, the Compagnia di San Giuliano decided to build an oratory in place of the shrine and set the fresco above the altar. The church stands in the middle of a large, octagonal loggia, under which there are tombstones and on which three doors open, each with lintels and carvings extolling the virtues of the Madonna. The interior houses an altar with massive marble columns on which is displayed the venerated fresco set in a precious Baroque frame. On the walls are seven paintings of various sizes with the subject of moments in the life of the Virgin, works by the Florentine painter Andrea Bamberini (16th century).