On the top of the Mount of Olives, a bit north of the "Pater Noster Church" is the "Mosque of the Ascension."
The current octagonal Crusader structure is built over a circular Byzantine church that commemorated the ascension of Jesus (Luke 24:50-52; Acts 1:1-12). The Crusader structure was originally open to the sky, but when the Muslims took over the building it was covered with a dome, and a mihrab was installed in the southern wall—turning the building into a mosque.
Today the building sits inside of a medieval octagonal enclosed area.
For a marvelous 2 minute video of Christian rites at this site Click Here.