At a depth of only two and a half metres from the surface of the tell M. de Sarzec came upon a building of the period of Gudea, of which only the angle of a wall remained. But, unlike the great Palace Tell, where the lowest diggings revealed nothing earlier than the reign of Ur-Bau, a deepening of his trenches here resulted in the recovery of buildings dating from the earliest periods in the history of the city. In accordance with the practice of the country, as each new building had been erected on the site, the foundations of the one it had displaced were left intact and carefully preserved within the new platform, in order to raise the building still higher above the plain and form a solid substructure for its support. To this practice we owe the preservation, in a comparatively complete form, of the foundations of earlier structures in the mound. At no great depth beneath Gudea's building were unearthed the remains of Ur-Ninâ's storehouse. Comparatively small in size, it is oriented by its angles, the two shorter sides facing north-west and south-east, and the two longer ones south-west and north-east, in accordance with the normal Sumerian system.[4] It was built of kiln-baked bricks, not square and flat like those of Gudea or of Sargon and Narâm-Sin, but oblong and plano-convex, and each bore the mark of a right thumb imprinted in the middle of its convex side. A few of the bricks that were found bear Ur-Ninâ's name in linear characters, and record his construction of the "House of Girsu," while one of them refers to the temple of Ningirsu. These may not have been in their original positions, but there is little doubt that the storehouse dates from Ur-Ninâ's reign, and it may well have been employed in connection with the temple of the city-god.