The mode of construction of the wall is likely to be misunderstood when we speak as we almost necessarily do of facings and filling and of bond tiles. The “facing” stones were small, roughly wrought, and set in much mortar; they formed outer skins to the concreted mass into which they tailed back. The whole was homogeneous. The method was analogous to the facing of concrete with triangular bricks notching back into the core. The tile courses in the City Wall were doubtless bonds, but they also divided the wall into strata locking up the moisture of the mortar from too rapid absorption and evaporation. I have little doubt that the wall was carried up a stratum at a time over long lengths; it would thus have been available as a defence from an early stage, and scaffolding would not have been required. The building of this wall and casting the ditch about it required a great constructive effort. A strip of ground some 100 feet wide must have been cleared as a preliminary. Then the immense quantity of stone required would have been brought by ships and barges. It is often said that old material was not re-used in the wall, but I can hardly think that two miles of chamfered plinth had to be provided out of new stone at the very beginning of the work. And material from destroyed monuments was doubtless broken up for the small facing stones. The lime-burning, brick-making, stone-cutting, as well as the actual building, called for much labour. It would be interesting to have the quantities taken out and an estimate prepared. The south wall along the river front is well described in _V.C.H._ Roach Smith, in an article in vol. i. of the _Archæological Journal_, recorded the fact that it had “alternate layers of red and yellow plain and curve-edged (_i.e._ flanged) tiles”; the rest being of ragstone and flint. It was founded on piles. In _The Builder_ (January 19, 1912) it is recorded that in digging for a foundation at No. 125 Lower Thames Street, between Fish Street Hill and Pudding Lane, there was found the base of the Roman wall resting upon long and thick timber balks laid crosswise, with piles beneath them; there were three courses of rough rag and sandstone capped with two courses of yellow bonding tiles, all in reddish mortar; what remained was about 3 ft. high and 10 ft. wide, and was at 24 ft. below the existing pavement. Full evidence of the course of the City Wall along the river front has been found (_Archæol._ xliii.). It may be noticed that in mediæval regulations foreign sailors might not go beyond Thames Street; that is, pass where the wall had been, into the City proper. This south wall, like the bastions, contained remnants of Roman monuments.