§428. The Columbaria.--From the family tombs were developed the immense structures mentioned in §422 intended to receive great numbers of urns. They began to be erected in the time of Augustus and seem to have been confined to Rome, where the high price of land made the purchase of private burial-grounds impossible for the poorer classes. An idea of their interior arrangements may be had from the ruins (Fig. 200) of one erected on the Appian way for the freedmen of Livia, the wife of Augustus. From their resemblance to a dovecote or pigeon house they were called _columbāria_. They are usually partly underground, rectangular in form, with great numbers of the niches (also called _columbāria_) running in regular rows horizontally (_gradūs_) and vertically (_ōrdinēs_). In the larger _columbāria_ provision was made for as many as a thousand urns. Around the walls at the base was a _podium_, on which were placed the sarcophagi of those whose remains had not been burned, and sometimes chambers were excavated beneath the floor for the same purpose. In the _podium_ were also niches that no space might be lost. If the height of the building was great enough to warrant it, wooden galleries ran around the walls. Access to the room was given by a stairway in which were niches, too; light was furnished by small windows near the ceiling, and walls and floors were handsomely finished and decorated. [Illustration: FIGURE 203. AEDICULA IN COLUMBARIUM] §429. The niches were sometimes rectangular in form, but more commonly half round, as shown in Figs. 200 and 203. Some of the _columbāria_ have the lower rows rectangular, those above arched. They contained ordinarily two urns (_ollae_, _ollae ossuāriae_) each, arranged side by side, that they might be visible from the front. Occasionally the niches were made deep enough for two sets of urns, those behind being elevated a little over those in front. Above or below each niche was fastened to the wall a piece of marble (_titulus_) on which was cut the name of the owner. If a person required for his family a group of four or six niches, it was customary to mark them off from the others by wall decorations to show that they made a unit; a very common way was to erect pillars at the sides so as to give the appearance of the front of a temple (Fig. 203). Such groups were called _aediculae_. The value of the places depended upon their position, those in the higher rows (_gradūs_) being less expensive than those near the floor, those under the stairway the least desirable of all. The urns themselves were of various materials (§437) and usually cemented to the bottom of the niches. The tops could be removed, but they, too, were sealed after the ashes had been placed in them, small openings being left through which offerings of milk and wine could be poured. On the urns or their tops were painted the names of the dead with sometimes the day and the month of death. The year is almost never found. Over the