The principal places where Roman remains are now to be seen are Lincoln, Dover Castle, St. Albans, Richborough Castle, Porchester, York, Cirencester, Leicester, and Colchester. But in all these there is little ornamentation or detail left, the remains consisting chiefly of plain walls, the masonry of which has peculiarities of character which mark its date. Of the masonry there are two principal varieties; the first, and that which is most readily recognised, consists of alternate layers or bands of pebbles, or small stones embedded in mortar, and tiles or flat stones. These bands consisted of three or four courses of tiles or stones laid through the wall, and were placed at two or three feet from each other, the intermediate spaces being raised with a sort of cement composed of mortar and pebbles, or sometimes rag-stones, or such materials as the country afforded. In this manner are built the Mint wall at Lincoln, the Jewry wall at Leicester, and the walls at Verulam (St. Albans), Porchester, Richborough, York, Pevensey, Chesterford, Colchester, Wroxeter, and Silchester. The other variety consists of walls formed of square stones or ashlar, as the Roman wall in Northumberland. These are sometimes very large, as in the north gate (or Newport gate), Lincoln. Smaller kinds of ashlar, of almost cubical blocks, occur in the multangular tower and other buildings at York. The mortar used in all these walls is in general mixed with pounded brick. It will not be necessary here to go into a description of all these buildings, but a few of the most remarkable may be mentioned; one of the most curious and interesting of these is the Pharos in the Castle of Dover, though it has undergone much alteration, particularly in the fifteenth century. "Wherever the outer casing is worn away, or has been removed by violence, the walls exhibit the usual mode of Roman building with the material of the districts; in this case with tufa or stalactite, brought perhaps from the opposite coast of France, and flint, with layers of large flat Roman bricks, some of them two feet long, each layer two courses deep, placed regularly and horizontally in the walls at equal intervals, or nearly so. No less than eight of these layers of brickwork are visible on the south-east side; other layers are apparently concealed by the external and subsequent casing of flint and stone, and where the casing of flint is perfect, quoins of stone appear at the angles. This tower is externally octagonal in form; internally the space enclosed forms a square. The doorway, recently blocked, is on the south side, and the arch, turned and faced with a single row of large Roman bricks, springs from a kind of rude impost moulding, somewhat resembling that of the Roman gateway at Lincoln; but this is not now visible. In the interior, the constructive features of the original Roman work were, before the entrance was closed up, far more visible and perfect than on