Why does Les conclude that the upper room was a large facility?
The upper room must have been a large facility because at least 120 people were meeting there. The number may have been only the men, with women and others besides, so the place had to be commodious and have a fair amount of room.
Les explains that after the Ascension the disciples returned to Jerusalem and congregated in an upper room. He says he does not know the exact situation, but it must have been a rather large facility because at least 120 people were meeting there. He even wonders whether that 120 was just the men, with women and others besides. Therefore wherever they met, it had to be commodious and have a fair amount of room. In the 10-day interval before Acts chapter 2, the 11 apostles were there plus other men, women, and probably children, and the number of names together was about 120.