In ro35 the ancient Porta Nigra, at Treves 9, fig. t t), was con verted into a church by the addition of an apse.' In m3S the church at Hersfeld was founded, and the crypt was consecrated in m4o, but the larger upper church was longer delayed. In Hersfeld there is also a pil lared basilica with unvaulted nave, choir, and transept; this was the work of the Cistercian monk Poppo von Stablo, who was also the architect of the church at Limburg. In to43 the Church of St. Severin at Cologne was dedicated, that of Mittclzell on the island of Reichenan in to4S, and in m49 that of Sta. Maria in Capitolo in Cologne (o/. 24, fig. S), the east ern portion of which, with the exception of the upper half of the prin cipal choir, is still extant in its original state. The latter is of the twelfth century; the vaulting of the side-aisles and the piers of the arcades with out doubt belong to the eleventh century. The middle aisle had, however, .a wooden roof, which was vaulted at a later date (fig-s. 2, 8).
Between m49 and m54 the church of the nunnery of Ottmarsheiin (fig. 6), begun at the beginning of the eleventh century, was consecrated; it is a copy of the minster-church at Aix la-Chapelle. The Cathedral of Constance was begun in to,52, and was dedicated in m58; it is a columned basilica, the nucleus of which—namely, the arcades of the nave, the arrangement of the transept, and the rectangular choir—is still extant. St. George at Cologne (a columned basilica) was founded in m59, as was also the Church of Sta. Maria ad Gradus, which was completed in m65, burned in mSo, rebuilt in m85, and demolished in 1817.
Under Archbishop Anno of Cologne (m56–m75) buildings were added to St. Ursula, Great St. Martin, St. Cunibert, and St. Pantaleon. To St. Gereon, a primitive round church, the chapel of St. Nicholas and a large choir with a crypt and two square towers were added in m67; in to68 the high altar of the crypt was consecrated, and in ro69 that of the choir. Three years earlier the Abbey-church of St. Michael at Siegburg, built under the same archbishop, was dedicated.
Large buildings were at times delayed considerably in their erection through either imperfect construction or accidental demolition; thus the Cathedral of Treves lay in ruins until Poppo (1017–m47) rebuilt it, to do which he used the three yet-standing columns of Constantine's building, erected a pier in place of the fourth column, and enlarged the building considerably toward the west. was first finished under Udo (died m77), the second bishop from Poppo. Though the polygonal west choir is yet later and its altar was consecrated in 1120, yet the exterior of the western portion is essentially a work of that date.
The Cathedral of Speyer was also lofig in building. When the emperor Henry III. was interred by the side of his parents in the still-unfinished church, in to56, the works were entirely suspended. Between to61 and 1072 a consecration took place. Then suddenly the structure became insecure, and the famous Benno, who in the mean while had become bishop of Osna bruck (ro6S--roSS), was called hither to strengthen the foundations, which the Rhine had begun to undermine. In row the emperor Henry IV., and afterward Bishop Otho of Bamberg, undertook the continuation of the cathedral, which the latter soon completed.
The Cathedral of Mayence, dedicated in .ro36, was a prey to the flames in roSr; the emperor Henry IV. commenced the rebuilding, yet after his death it resembled a ruin, and it was in the twelfth century re-erected iu its present condition as a vaulted structure. Barrio's structure had a flat ceiling; particulars of Henry IV.'s new building have not come down to us; so that it must remain uncertain whether he commenced the vaulting.
Hirschart the diocese of Speyer the Hirschau Convent was founded in the ninth century, and after it had remained uninhabited for half a century was again peopled in the eleventh century. Its church —a small basilica with columns, block capitals, and vaulted side-aisles was consecrated in ro7r. The convent increased so rapidly that a new one was built between ioS3 and row, and in the latter year its church was consecrated. It is not known whether columns or pillars supported the walls of this church, which is now destroyed, but we know that it had a flat wooden ceiling, which was renewed in the year i5oo. St. Severin at Cologne was restored roS9-1099.
Further Dczr/opmeni of Architecture: —One of the most im portant steps in the development of the architecture of the Middle Ages was the cross or groined vaulting of the nave, as in the cathedrals of Speyer and Maveiice, and a number of other buildings. Through this the complete monumentality of the building was consummated, and that perfect harmony of the interior obtained which the Byzantine system had reached by the use of cupolas; but it called for greater wall-masses to withstand the lateral thrust exercised by these large vaults. Even in the Christian-Roman period the apses were vaulted; the square spaces of the chancel and of the transepts and the crossing of nave and transepts were next, in the eleventh century, covered with vaults, even in cases where the nave remained unvaulted and only the side-aisles—or not even these --were vaulted.