The marble was quarried from Mount Pentelicus and transported 19 km to the acropolis of Athens. A persistent question has been whether it was carved "in situ". Just below the moulding and above the tenia there is a channel 17 mm high that would have served to give access to the sculptor's chisel when finishing the heads or feet on the relief; this scamillus or guide strip is the best evidence there is that the blocks were carved on the wall. Additionally, on practical grounds it is easier to move a sculptor than a sculpture, and to use a crowbar to put them into place, potentially, could have chipped the edges. No information is recoverable on the workshop, but estimates range from three to 80 sculptors on the basis of style. However, American archeologist Jenifer Neils suggests nine, on the grounds that this would be the least number necessary to produce the work in the time given. It was finished with metal detailing and painted. No colour, however, survives, but perhaps the background was blue, judging by comparison with grave stelae and the paint remnants on the frieze of the Hephaisteion. Possibly figures held objects that were also rendered in paint such as Poseidon’s trident and the laurel in Apollo’s hand. The many drill holes found in Hera’s and Apollo's heads indicate that a gilded bronze wreath would probably have crowned the deities.