How many people were in the upper room on the Day of Pentecost (Acts 2:1-4)? Where was the crowd of diaspora Jewish pilgrims who heard these men and women speak in their own "native languages"? Where was Peter's Pentecostal sermon preached?
I have always been taught that 120 of Christ's disciples assembled in an upper (second-floor) room of a Jerusalem residence after the resurrection and ascension of Jesus and waited patiently there until they were filled with the Holy Spirit and spoke in other tongues (Acts 2:1-4).
But a closer look—and some practical thinking—undermines this picture. It is difficult to imagine a second-floor room of any first-century Jerusalem residence holding 120 occupants. It is equally curious how the "other languages" were heard by those outside the room—especially when the hearers swelled to a crowd. It is altogether impossible to believe that Peter's sermon addresses the crowd from within the confines of the upper room.
The problem here is the human tendency to run details together in adjacent sections of an episodic narrative. Remember, Acts is a continuation of the Gospel of Luke and follows the same presentation of events as discrete episodes that may or may not be connected in sequence, location, or time. The Gospel narratives offer a collection of episodes—no doubt arranged around the rough outline of the life of the historic Jesus. These episodes sometimes abruptly shift in time and location, but more often, the episodes are delimited and tied together by clear transitional phrases that indicate (suggest) a change in time, location, or situation.
With this in mind, let's take a close look at Acts 1 & 2 and at our assumptions about when, where, and to whom the Pentecostal experience occurred.
Following the literary introduction of the book of Acts (Acts1:1-3) which ties the current volume to the earlier Lucan Gospel and the narrative to the passion of Jesus, Acts 1 & 2 divides into 7 distinct episodes, each beginning with a clear transitional phrase.
Acts 1:4-11 - The Ascension of Jesus (beginning with "on one occasion").
Acts 1:12-14 - Return of the Eleven to Jerusalem (beginning with "then"). Here the apostles (the Twelve minus Judas), Mary, the mother of Jesus, and the brothers of Jesus go to the second-story room of a Jerusalem residence which was probably where they had been staying since the resurrection of Jesus. This is probably fifteen or sixteen people.
Acts 1: 15-26 - The Election of Matthias (beginning with "in those days"). 120 people are present, but no location is specified. It is doubtful this occurred in the upper room of a residence since such a space would hardly hold 120 people.
Acts 2:1-4 - Spirit's Outpouring at Pentecost (beginning with "when the day was fully come"). The time is designated as early in the morning on the feast of Pentecost. The location is designated very loosely ("the house where they were sitting"). The NT word for house can refer to a residence, a public building, a sheltered area, etc. No indication is given of the number in attendance. (This is at least the following day—or perhaps several days after—the election of Matthias. Night has past and day has come.)
Acts 2:5-13 - Gathering of the Crowd Brought by the Public Display of Glossolalia (beginning with "now there were"). This appears to be a public place capable of holding a crowd. This is clearly a place where diaspora pilgrims would gather. There is certainly no indication that the crowd entered a room of any sort. The best guess for the location would be the temple grounds on the feast day.
Acts 2:14-40 - Peter's Sermon (beginning with "then Peter"). This presentation assumes a public area large enough to hold the Jewish pilgrims at the feast. Again the temple grounds make the most sense.
Acts 2:41-47 - Author's Summary of the Aftermath/Results of Peter's Sermon. This section describes a period of time ("day by day") of public life in the temple and table fellowship in homes.
If we are to take these episodes seriously as separate events (some obviously in sequence), then there is no reason to conflate or "smudge" the details of the events together. There is no reason to assume that the 120 that elected Matthias were in the same upper room where the Eleven, Mary, and Jesus' brothers set up residence. There is certainly no reason to think that the Pentecostal experience took place in this same upper room to this same 120 people.
Don't get me wrong. I don't think this is a great interpretive insight. Neither would I even think about parting company over how the details of these stories are conflated.
But the consistent presentation of the "facts" that Spirit was poured out on 120 in the upper room on Pentecost bears witness to our tendency to "run together" the details of adjacent episodes in the Gospels and Acts. This calls us to a more careful and closer reading of these texts, taking seriously the literary conventions upon which they were built.