In the Acts of the Apostles, it is narrated that the apostles received the Holy Spirit at Pentecost.
However, the exact location of this momentous event is not clearly marked, and many biblical scholars debate where it could have happened.
Immediately after the ascension of Jesus, it is stated that, "When they entered [Jerusalem] they went to the upper room where they were staying" (Acts 1:13).
It is clear that after the ascension the apostles went to the "upper room" or "cenacle."
Then the Acts of the Apostles skips in time to the events of Pentecost.
This is where the text is somewhat ambiguous. While the English translation says, "house," some biblical scholars claim that the author of Acts was referring to the "house" of the Lord.
For example, later in Acts we find the temple referred to as a "house."
Another argument for the "house" being the temple is from the Jewish perspective, according to a writer at Torah Portions.
This location could also accommodate the large number of disciples who were baptized on Pentecost, as narrated in Acts 2.
Nevertheless, biblical scholars disagree on the interpretation of this passage, and local tradition still claims Pentecost occurred in the "upper room."
Whatever the location, what is true is that Pentecost did occur in Jerusalem and marked a pivotal point in the beginning of the Catholic Church.