Some of the sources of the Claudia were in the lake of S. Lucia, below Subiaco, between that and Vico Varo (see 1536). In its course through the hills the _specus_ is almost entirely underground, and cannot be shewn in photographs; but the line of its course is shewn in the map of the aqueducts from Rome to Subiaco, reduced by photography in Nos. 1967* to 1984*, especially in Nos. 1976*, 1978*, 1979*, 1981*. It crosses mountain streams on the bridges called Ponte Lupo (1532) and Ponte di S. Antonio (1530); and an inscription relating to it, of _A.D._ 88, is given in No. 1976*. When it reaches the level ground of the Campagna, nearly on the same level as the hills of Rome, the _piscina_ for it is subterranean, and only the summit of this is visible, looking like a _tumulus_ only (688); but from this the _specus_ is seen to emerge, at first only just above ground, but gradually getting higher (or the soil, in fact, is getting lower), until it is carried on the grand series of arches or arcades across the country, which remain nearly perfect for some miles, as far as the Sette Bassi and Roma Vecchia. In 1002, a long line of this arcade is shewn with the Claudian _specus_ upon it, and the Anio Novus over that in many places; the two can readily be distinguished, by the Claudian being built of large blocks of stone (with the edges chamfered off), and the Anio Novus being faced generally with brick, occasionally with _opus reticulatum_. Nearer to Rome, this fine arcade has been very much damaged, or carried off altogether as building material by the farmers, and by the engineers of Pope Sixtus V. to build the Aqua Felice; but some portions of the old arcade remain, and are shewn in No. 1006, where the distinction between the two _specus_ comes out very clearly. In 1005, two of the brick arches with which it had been strengthened by Trajan are shewn, the stone-work having all been carried away.