Jerusalem, Church of the Holy Sepulchre
It seems likely that there were mosaics in the great Church of the Holy Sepulchre from its foundation in the fourth century, and certainly added to it and its multiple chapels as repairs and renovations throughout its life. By the twelfth century, the church contained a considerable collection of mosaics, including a scene described as the Exaltation of Adam (probably the Anastasis), with the Virgin, Baptist and Apostles below in the apse, and depictions of the Ascension, Pentecost and Annunciation, as well as various Old Testament figures. Of all of this, only a fragment of the Ascension now survives on the ceiling of the Calvary chapel, ignored by visitors more interested in the stone of Golgotha. In the middle of much, much later mosaics (blue background, plant scrolls and all sorts) is an egg-shaped fragment outline in red and gold. It looks out of place because it is a lot dirtier and less easy to see than the rest. That's because it's 12th century not 19th or 20th century. Christ is seated on a rainbow, with his feet dangling, right hand uplifted in a blessing gesture. He's in a mandorla, a glory, made up of ovals of white (silver?) grey and blue tesserae. The inscription is in Latin and says 'Ascensio'.
Other fragments of twelfth-century mosaic survive in situ: in the Chapel of the Franks at the entrance between it and the Calvary church, some bands of geometric patterns, comparable to decoration in the Dome of the Rock, survive in two niches above sculptural decoration.