The large furnished upper-story room where Christ ate the Last Supper with His disciples (Mark 14:13-16; Luke 22:10-13) and where the disciples gathered to wait for the promised Spirit (Acts 1:13-14) before Pentecost. The Greek anagaion (upper room) was a common architectural feature of first-century Palestinian houses — an upstairs room used for gatherings, meals, and prayer. Christ's instructions for finding it (a man carrying a pitcher of water would lead the disciples to it) carry their own signal: men did not typically carry water-pitchers (women did), so the instruction was a pre-arranged sign. In the upper room Christ instituted the Lord's Supper, washed the disciples' feet (John 13), gave the upper-room discourse (John 14-17), and prayed His high-priestly prayer. After the resurrection and ascension, the same kind of upper room (Acts 1:13) became the gestational space of the early church. From upper room to Pentecost — the foundational arc of the apostolic mission.