Where did Jesus tell his disciples to wait for the Holy Spirit?

What did the disciples ask Jesus about in Jerusalem?

What did Jesus say the disciples would receive when the Holy Spirit comes?

What incredible event did the disciples witness?

Who appeared beside the disciples as they looked up to the sky?

"And when the Holy Spirit comes, you will receive power. And you will tell everyone about me, everywhere - from Jerusalem to the farthest corners of the earth." - Acts 1:8