Every so often when touring a Church, one runs across a polyphonic group practicing at a side altar. These are always some of the most interesting performances. The singers are dealing with all kinds of noise in the background, and you get to see what it is like for them to sing this great music in a rehearsal context. I can sit and be mesmerized by such groups for as long as they are willing to stay and sing. You can also see the effect of this music on others. Perhaps it is the first time that tourists have heard such sounds.
Here is a nice video of an independent group of singers assembled in Salisbury Cathedral. They are singing O Sacrum Convivium by Thomas Tallis.