What Constitutes a Vital Congregation?

The Vatican has ordered that Bishop Richard Lennon of the Cleveland, Ohio Diocese reopen thirteen churches that he had ordered closed. Thirty-seven other churches he ordered closed remain so. All thirteen congregations had appealed the closures to Rome.

While the Vatican's rationale for reopening the parishes was due to Bishop Lennon's failure to "properly follow church law and procedures," parishioners in the thirteen congregations argued that they remained vital churches.

My interest in this post has nothing to do with whether or not Bishop Lennon went about this in the prescribed way, nor am I in a position to judge whether or not these church were vital when they were closed. What I am interested in is what exactly constitutes a vital congregation. Is it simply because a church building is historic or that it's congregation has a storied history? Is vitality measured because one's family has attended a particular parish for three or four generations? Is a church vital because it contains precious art and magnificent architecture?

I don't think there is only one or two things that make a church vital, but I would say there are some essentials, and that without those essentials a congregation's vitality is in serious doubt.

I have some thoughts on this, but I would like to hear from you. What do you believe constitutes a vital congregation? I am not looking for an exhaustive answer. I just want to know what you think is essential for congregational vitality.