The Roman Baths of Vasto are famous for two large mosaics discovered during excavation campaigns in 1974 and 1997.
The first mosaic, known as the Marino Mosaic, measures approximately 38 square meters. It was initially unearthed in 1828 during work near the convent of San Francesco, then a royal sub-prefecture. At the time, it was reburied as digging beneath the building was deemed impractical, leaving its rediscovery to future generations. In 1974, the mosaic was uncovered again during the construction of the Arena delle Grazie, removed, and transferred to the Archaeological Museum of Palazzo d’Avalos. In 1997, after restoration, it was returned to its original location at the Baths.
The mosaic features floral decorations, with two central crosses depicting sea horses and fish, surrounded by ellipses featuring dolphins and octopuses. At its center is a roaring sea tiger with a crested neck, raised paw, and fish tail. This basin, located near a heating system or “praefurnium,” was likely a caldarium, used for hot baths.
The second mosaic, the Neptune Mosaic, spans 170 square meters, making it the largest Roman mosaic on the Adriatic coast. Unearthed in 1997, part of it remains covered by the sacristy of the church of Sant’Antonio. Its design includes stylized plant motifs forming thirteen four-leaf clover patterns. At the center stands Neptune holding a trident and a dolphin. Surrounding fields depict three Nereids (two on horseback, one on a dragon), a dolphin’s tail, three tritons, and a cupid. The mosaic suffered some damage during 19th-century excavations for the Bourbon Subintendency building. This basin, likely a frigidarium for cold water baths, lacked evidence of heating systems, confirming its function.
Both mosaics share unique features, such as the use of white tiles in black designs and ivory-colored tiles common in African floorings but rare in Italy.
These details suggest they were crafted by non-Italian artisans working in Histonium in the first half of the second century AD.