Why do most churches meet on Sunday? Most protestant churches (and possibly Roman Catholic churches?) have their main public meetings on Sundays. Why Sunday?

Note: I'm not asking why do Christians celebrate the Sabbath on Sunday, but why do they meet for their main church services on Sunday. Maybe it is the same reason, but I think it's a different question
Christians meet on Sunday in remembrance of Jesus's resurrection, which was on the first day of the week.  Historical evidence shows that this has been Christian practice since early times, perhaps even since the very beginning of Christianity.  The 2nd century apologist Justin Martyr certainly believed so:


  But why is it, you ask, that we gather on the Lord's Day to celebrate
  our solemnities?  Because that was the way the Apostles also did.
  
  -- De Fuga in Persecutione, XIV: 11