You'll see the older stuff (medieval and Renaissance) in modern editions in a variety of pitches, depending on who wrote it down.
Our choirmaster transposes to take advantage of our room (he says the room is the "extra singer" in the ensemble). You have to make adjustments because most American rooms do not have the advantage of 8 foot thick stone walls - which really kills your bass singers because siding just doesn't bounce low tones like thick stone walls do.
We're fortunate to have a very good room - the proportions are correct and although we don't have stone we have brick veneer over poured concrete. Chamber groups and touring singers are always trying to get the church for concerts.
And you notice the bouncing effect more in medieval and Renaissance music because it's written for small ensembles, not the "cast of thousands" that came in with the Romantics. This is a pic of the greatest composer of his day, Johannes Ockeghem (in the glasses), with his choir - all eight of them.
Josquin, by the way, wrote a lament ("deploration") on the death of Ockeghem, who was his master. It really is gorgeous, and the interesting thing is that Josquin pays homage not only with the words, but with the music, imitating some of Ockeghem's characteristic techniques - particularly in the bass lines. Ockeghem was the first to really take advantage of the lowest male voices in ensemble singing - he was noted himself for a very deep and resonant voice.
Deploration sur la mort Johannes Ockeghem ("Nymphes des bois")
Nymphs of the woods, and goddesses of the fountains,
skilled singers from all nations,
change your voices so clear and high into shrill cries and lamentations,
for Atropos, that great satrap,
has caught your Ockeghem in her trap,
[this is an attempt to catch the pun in French]
music's true treasure and masterpiece,
learned and handsome and by no means stout
it is great sorrow that earth must cover him.
Put on your mourning garments,
Josquin, Brumel, Pierchon, Compère, (all great composers)
and weep great tears from your eyes
you have lost your good father.
Grant to them eternal rest, O Lord,
and may perpetual light shine on them.
Cantus firmus: May he rest in peace. Amen.