338 EOMAN ARCHITECTURE. Part I. 218. Plau of Porta I^igra at Treves, Scale 100 ft. to 1 in. or gallery that runs across the top of them, replacing the attic of the Roman arch, and giving a degree of lightness combined with height that those never possessed. These gates were certainly not meant for defence, and the apartment over them could scarcely be applied to utili- tarian purposes ; so that we may, I believe, consider it as a mere orna- mental appendage, or as a balcony for display on festal occasions. It appears, however, to offer a better hint for modern arch-builders than any other example of its class. Even more interesting than these gates at Autun is that called the Porta Nigra at Treves ; for though far ruder in style and coarser in detail, as might be expected from the remoteness of the province where it is found, it is far more complete. Indeed, it is the only example of its class which we possess in anything like its original state. Its front consists of a double archway surmounted by an arcaded gallery, like the French examples. Within this is a rectangular court which seems never to have been roofed, and beyond this a second double archway similar to the first. At the ends of the court, projecting each way beyond the face of the gateway and the gallery sur- mounting it, are two wings four stories in height, containing a series of apartments in the form of small basilicas, all similar to one another, and measuring about 55 ft. by 22. It is not easy to understand how these were ap- proached, as there is no stair and no place for one. Of course tlicre must have been some mode of access, and perhaps it may have been on the site of the apse, shown in the plan (Woodcut ' Xo. 218), which was _ ulded when the 219. View of the Porta Nigra at Treves. building waS COll- vei-ted into a church in the Middle Ages. These apartments were probably originally used as courts or chambers of justice, thus realizing, inore nearly than any other European example I am acquainted with, the idea of a gate of justice. Notwithstanding its defects of detail, there is a variety in the out-
