Cross of Lothair, Processional cross in Aachen Cathedral Treasury, Germany

The Cross of Lothair is a crux gemmata, a jewelled processional cross, in the Aachen Cathedral Treasury. Its oak core is covered with gold on the imperial side and gilded silver on the reverse, and it measures 50 cm high, 38.5 cm wide and 2.3 cm deep. The front holds 102 gems and 35 pearls, with a first-century sardonyx cameo of Emperor Augustus at the crossing.

The cross was made in the last quarter of the 10th century, around 985, in the Rhineland, probably in Cologne, and may have been donated by Otto III. Its name comes from a 9th-century rock crystal seal of King Lothair II set into the lower arm. It was given to Aachen Cathedral soon after it was made.

The cross is still carried in procession on high feast days and placed beside the main altar during Mass at Aachen Cathedral. Its name comes from a 9th-century rock-crystal seal of King Lothair engraved with "+XPE ADIVVA HLOTARIVM REG" (Christ, help King Lothar), set into the lower arm where comparable crosses show a donor portrait.

Visitors can view this medieval artifact at Aachen Cathedral Treasury. The cross remains in active use during major religious celebrations held at the cathedral.

The 102 gems and 35 pearls were probably meant to total 144, the number of the Heavenly Jerusalem; seen from the side, the gem settings form small temple buildings. The lowest large stone is a rock crystal seal of Lothair II inscribed "+XPE ADIVVA HLOTARIVM REG".