The whole complex of the Forum Baths, Thatcher concludes, shows a sophistication in the use of radiant heating well beyond what modern engineers have achieved. Though brick construction made Ostia more nearly fireproof than a modern city of frame dwellings, the grain for the dole stored in the city’s numerous warehouses was too valuable a commodity to risk, so a cohort of firemen detached from the main corps in Rome was kept at the ready in barracks behind the Baths of Neptune (_Reg._ II,v). The barracks, built under Hadrian, surround an arcaded courtyard with rooms opening off. A latrine with a shrine in it thriftily combines cleanliness with godliness. At the end of the courtyard opposite the entrance is a platform which still bears the bases of statues of Emperors worshiped by the firemen as a part of the Imperial cult. As at Pompeii, so at Ostia, the houses are the most interesting part of the city, not least because Ostian houses differ completely in plan from Pompeian ones. The great majority are apartment houses, tall, many-windowed brick blocks, with or without shops on the ground floor. They were designed to be rented out in flats, with separate access to the upper stories from the street. Some have balconies, opening both on the street and on garden courtyards where many families shared the pergolas, fountains, trees, shrubs, pools, and statue-studded lawns, as they shared also the large common latrines. The Casa dei Dipinti (_Reg._ III,iv; see Fig. 10.3) is such a block, built in Hadrian’s reign. The ground-floor flats have mosaic floors and paintings of mythological scenes, figures of poets and dancers, landscapes, and fantastic motifs. At the end of the garden is yet another of Ostia’s combinations of the useful with the ornamental: a number of large _dolia_, terracotta jars sunk in the ground for storing oil or grain. Despite the panegyrics of the excavators, there is a certain deadly sameness about these flats where the lower middle class lived their lives of quiet desperation, as they do in the unfashionable quarters of Rome today. [Illustration: FIG. 10.3 Ostia, Casa dei Dipinti, Gismondi’s reconstruction. (Alinari)] The occupants of Ostia’s flats were largely tradesmen or minor civil servants. Their livelihood came from Ostia’s two artificial harbors (Fig. 10.4). The earlier, begun under Claudius in A.D. 42, is now the site of a military airport, whose engineers have preserved the traces (Fig. 10.5) of the two curving moles which enclosed a basin over 850,000 square yards in area. Ancient sources say there was an artificial island between the arms of the moles, with a lighthouse on it which became the symbol of Ostia: it is often figured in mosaics. A canal, now the Fiumicino branch of the Tiber, connected the harbor with the main stream.