“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.”
King James Version (KJV)
1:13 They went up into the upper room - The upper rooms, so frequently mentioned in Scripture, were chambers in the highest part of the house, set apart by the Jews for private prayer. These, on account of their being so retired and convenient, the apostles now used for all the offices of religion. #Matt 10:2|; Mark 3:14; Luke 6:13.
Ac 1:13 Went into an upper room. A guest chamber on the second floor. Where abode. All the apostles are named except Judas Iscariot, who had fallen away and was now dead.