The upper room was where Jesus shared the Last Supper with his disciples, washing their feet and instituting communion. After his ascension, the disciples gathered there in prayer, and it was near here that the Holy Spirit came at Pentecost.
The upper room marks intimate moments of Jesus with his own, and the quiet, prayerful beginning of the church that would reach the world.
The Upper Room in Scripture
And when they were come in, they went up into an upper room, where abode both Peter, and James, and John, and Andrew, Philip, and Thomas, Bartholomew, and Matthew, James the son of Alphaeus, and Simon Zelotes, and Judas the brother of James.