Palazzo de Beaumont Bonelli, Noble palace in Taranto, Italy.

Palazzo de Beaumont Bonelli stands at Corso Vittorio Emanuele II 39 in Taranto's old town, on the Ringhiera del Mar Grande. The late-17th-century noble palace was built over earlier underground rooms cut by the Spartans, who quarried the 175,000-year-old calcarenite to build the city. Its restored piano nobile and the Ipogeo Bellacicco below, with four halls 5 to 8 m high reaching 16 m below street level, now host the Museo Spartano.

The palace was built at the end of the 17th century over pre-existing underground rooms carved by the Spartans, who quarried the calcarenite bank to obtain building material when they founded Taranto in 706 BC. The de Beaumont Bonelli family lived here until the early 20th century, when the family died out and the palace was sold. In 2002 the Bellacicco family restored the central core of the noble floor and the underlying hypogeum, and since 2015 the hypogeum has housed the Spartan Museum of Taranto.

The hypogeum's rooms are named after Spartan founder Phalanthus and his wife Ethra, linked to the 706 BC founding of Taranto. Since 2015 the underground halls house the Museo Spartano, and the site is managed by the Associazione Culturale Filonide, which runs the visits.

The restored noble floor and the Ipogeo Bellacicco are entered at Corso Vittorio Emanuele II 39, on the Ringhiera del Mar Grande in the old town; visits to the hypogeum and the Spartan Museum are run by the Filonide cultural association. The underground route descends four levels to 16 m below street level, so expect stairs and a cool, damp environment.

The hypogeum beneath the palace is listed in the regional register of artificial cavities of Puglia under number PU_CA 668, the only underground space in Taranto's old town reviewed by the Puglia Speleological Federation. Its four halls reach 16 metres below street level and 4 metres below sea level.