Tomb I is the oldest built tomb in the Necropolis, with finds dating from the first half of the 6th century BC. Internally, it measures 3.60 m. long x 1.20 m. wide x 1.35 m. high. On the south-west side of the tomb one of the stone slabs from the roof survives intact. An impressive feature is the stepped arrangement of the stone courses around the burial chamber.
The internal surfaces of the tomb were carefully coated with plaster and an impressive purple band 9.0 cm. wide runs around the burial chamber at a height of 0.82 m. above the floor. Above this another band is visible, which is bounded by two rows of nails and a painted line. These nails are believed to have secured a wooden board to the walls, on which were fastened (also with iron tacks) bone plaques decorated with scenes of women, shield-bearing warriors, chariots, animals, water birds etc. In addition to these plaques, which are masterpieces of miniature art, a number of other objects were gathered from the interior of the tomb, including the fragments of a black-figure oinochoe with a depiction of Dionysus and a group of maenads in procession, a number of figurines with heads cast from moulds and hand-made bodies that preserve traces of paint on the clothes, and a fragmentary gilded silver sheet depicting the Cyclops Polyphemus sitting down opposite two sheep with men tied underneath them.
Outside the tomb a large section of a column drum was found, together with an Ionic capital, the top surface of which displays evidence of having supported a statue, probably that of a sphinx.