It is held forty days after Easter, or ten days before Whitsunday, in celebration of Christ's ascension into heaven forty days after the resurrection.
The Ascension of Isaiah supply much information on this subject.
It always falls on a Thursday, and the day is known as Ascension Day, or Holy Thursday.
In the Ascension of Isaiah (1st century A.D.) Seth is seen in heaven.
On the mount of Olives are the Russian church, tower and hospice, near the chapel of the Ascension; the French Paternoster church; the Carmelite nunnery; and the Russian church of St Mary Magdalene, near Gethsemane.