Identification: Insula Tiberina During the printing of PM 1960, L. Cozza was able to match this fragment with fr. 32cde and to the now lost fr. 32b, and he renamed it 32f (hence its dual appearance in pls. 30 and 54). This allowed Cozza to identify the fragment as belonging to the Tiber Island (PM 1960, p. 93). Referred to in antiquity as the insula Tiberina, insula Tiberis, insula Tiberini, insula Aesculapi, or simply insula (part of one of these labels is visible in fr. 32a), the tiny island occupied a nodal role in Rome's earliest history, when it was the only point at which the treacherous Tiber could be crossed by a ferry (LTUR III, p. 99). Nevertheless, the island is not mentioned in ancient sources until the 3rd c. BCE, when it became the site of the imported cult of Aesculapius. Its use as a center of healing continued through the Middle Ages to this day. Even before the 1st c. BCE the island was surrounded by stone foundations to give it the shape of a ship (LTUR III, p. 100). This fragment probably shows a small section of the slightly curved S edge of these foundations, more of which are visible in fr. 32cde (see reconstruction in AG 1980, pl. 34). Remains of the "stern", with a depiction in relief of a serpent coiled around a staff, still exist on the SE tip of the island.

Identification: Tiberis L. Cozza's ability to join this fragment to fr. 32cde demonstrates that the blank area to the right of the curved line represents the Tiber (PM 1960, p. 93). Italy's third longest river, the Tiber winds its way through Rome about 25 km before it drains into the Tyrrhenian Sea. In antiquity, only Tiber Island and perhaps eight bridges interrupted its 5.6 km long stretch between the Aurelian Walls (see LTUR V, fig. 46). For the Romans, the Tiberis (other appellations were Albula, Thybris and Tiberinus) was a provider of both bounty and frustration. It was the vital trade route between the city and the outside world; fishing in its waters provided food; and until the construction of Rome's aqueducts it was the major source of drinking water. However, the Romans struggled endlessly to keep the waterway navigable and to control the violent and frequent floods. Commercial buildings such as horrea were constructed along its banks as early as the 2nd c. BCE., and later the villas, horti, and mausolea of the upper class vied for space along the river with the apartments and cemetaries of the less fortunate (LTUR V, pp. 69-73). Remains of these buildings, especially of the commercial structures and the cemetaries and residences of the poorer classes, were largely destroyed when retaining walls were constructed on both sides of the river at the end of the 19th c. (It was during the construction of the Tiber embankment along the Via Giulia in 1888 or 1898 that a plethora of FUR fragments was discovered.) The appearance of these non-monumental structures on the Marble Plan is therefore of great significance. Despite its important role in Rome's economy and social and political history, the Tiber is not outlined on the Marble Plan. It appears simply as a blank space whose shape is discernible only through the construction that frames it on both sides (see for example fr. 24d). Although color was used to highlight certain buildings and streets on the Plan, there is so far no evidence to show that the river was emphasized in any way (except a possible label, Tiberis, inscribed in fr. 200b [Rodríguez-Almeida 1992, pp. 59-60]).

Significance Considering the many blank areas on the Marble Plan (representing gardens, arenas, temple precincts, courtyards, or areas near the edges of the Map, in addition to the Tiber) and given the fact that about 36 percent of the surviving FUR fragments are blank, it is an astonishing feat for L. Cozza to have identified this fragment. He was able to do so partially from observing the quality of the marble, its thickness, smooth back, and partially because the fragment was broken along parallel lines, characteristic of pieces belonging to slab V-13 (AG 1980, pp. 115-118 and pl. 24).

Text by Tina Najbjerg