I posted these photos below on another post. But as I look at them, I realize that the beautiful altar was sliced away from the reredos in order to allow it to be “freestanding” and for Mass to be celebrated either facing the nave or facing the apse, also know as facing the people or facing God.
There is no violence done to this sanctuary or altar/reredos. This is the way to do it and in fact I did it at the Church of the Most Holy Trinity in Augusta and very successfully. I wanted to do it at St. Joseph Church in Macon, but was advised by a structural engineer that doing so might make the reredos top heavy and with the potential to collapse forward and more than likely on me as I celebrated Mass facing the people. Of course, some of the people at St. Joseph would have been thrilled for me to be sacrificed on their altar in front of them, but I digress.
This is The Church of Our Lady of the Assumption and Saint Gregory Catholic Church on Warwick Parish, London, UK. (I ask John Nolan if he knows of this church?)
But here is the way to do a renovation of a Catholic sanctuary right: