An ancient tradition connected Herculaneum with the name of the Greek hero Heracles, an indication that the city was of Greek origin.The particular circumstances of the burial of Herculaneum, unlike those of Pompeii, led to the formation over the city of a compact mass of tophaceous material about 50 to 60 feet (15 to 18 metres) deep. Although this layer made excavation very difficult, it preserved Herculaneum and prevented tampering and looting. The special conditions of ground humidity made possible the conservation of wooden frameworks of houses, wooden furniture, the hull of a sizable boat, pieces of cloth, and food (carbonized loaves of bread left within ovens). Thus, Herculaneum offers a detailed impression of private life that is only difficulty to achieve in other centres of the ancient world. Excavation began in the 18th century, bringing to light the first houses of Herculaneum, among which was the peristyle of the House of Argus. The larger decumanus (“main road”) forms one side of the quarter of the ancient forum with its public buildings. The insulae (“blocks”) to the south of the decumanus are laid out in a strictly geometric pattern facing the cardines (“crossroads”). Many of the nobler houses afforded their patrons a view of the bay. Inside the residential quarter, houses of rich republican and patrician construction alternate with houses of the middle class (such as the Trellis House), also finely decorated, or with commercial houses and workshops.The public monuments uncovered include the palaestra (sports ground), with a large portico surrounding a vast central piscina (swimming pool), and thermae (baths), one of which adjoins the former beachfront. This bath is in a remarkable state of preservation, having remained largely protected against the pyroclastic flows of the eruption.