Manchester united have reached Champions League 5 times. They reached in 1968,1999,2008,2009 and 2011.
The Champions League final will be played in the Olympiastadion in Berlin, Germany.
Arsenal have only reached the semi finals of the Champions league twice. They reached the stage in 2006 and 2009.
Wembley Stadium, London.
At the Luzhniki Stadium in Moscow, Russia.
wembley Stadium in England
Celtic park, without question
They reached the semi final in 2001.
This is not possible as the winners of the Champions League and Europa League get direct entry to the next UEFA Champions League. Hence this case can't happen in the Champions League.
Stadio Olimpico in Rome