The treatment of a mosaic floor is an altogether different problem. While the floor as a whole, with its ornamental designs, is left in place, fine mosaics representing paintings, which are delicate and easily destroyed, are wisely taken up and placed in the Museum. NOTES TO PLAN I The Regions are given as they were laid out by Fiorelli (p. 34), the boundaries being marked by broken lines. The Insulae are designated by Arabic numerals. Stabian Street, between Stabian and Vesuvius gates, separating Regions VIII, VII, and VI, from I, IX, and V, is often called Cardo, from analogy with the _cardo maximus_ (the north and south line) of a Roman camp. Nola Street, leading from the Nola Gate, with its continuations (Strada della Fortuna, south of Insulae 10, 12, 13, and 14 of Region VI, and Strada della Terme, south of VI, 4, 6, 8), was for similar reasons designated as the Greater Decuman, _Decumanus Maior_; while the street running from the Water Gate to the Sarno Gate (Via Marina, Abbondanza Street, Strada dei Diadumeni) is called the Lesser Decuman, _Decumanus Minor_. The only Regions wholly excavated are VII and VIII; but only a small portion of Region VI remains covered. The towers of the city wall are designated by numbers, as they are supposed to have been at the time of the siege of Sulla, in 89 B.C. (p. 240). [Illustration: PLAN I.--OUTLINE PLAN OF POMPEII.] CHAPTER V _A BIRD'S-EYE VIEW_ The outline of Pompeii, with its network of streets, may be traced on the accompanying plan. The city took its shape from the end of the old lava stream on which it lay, which ran southeast from Vesuvius. It formed an irregular oval a little less than four fifths of a mile (1200 metres) long and a little more than two fifths of a mile (720 metres) wide in its greatest dimensions. On three sides, west, south, and east, the wall of the city ran along the edge of the hill; on the northwest side, between the Herculaneum and Capua gates, it passed directly across the ridge formed by the lava. The eight gates are known by the modern names given on our plan. Two of them, the Herculaneum and Capua gates, lie at the points where the wall comes to the edge of the lava bed on either side; the streets that led from them descended to the plain. At the Herculaneum Gate the much travelled highway from Naples, passing through Herculaneum, entered the city; the Capua Gate does not seem to have been built to accommodate a large traffic. Between these two lay the Vesuvius Gate, through which the Pompeians passed out upon the ridge toward Vesuvius.