Both of the above are the main square right around sunset.
You can't take pictures inside the cathedral, but it houses the famous Cusco Last Supper. Here's a link for the cathedral:
And here's a link to the painting. You have to scroll down. It's hilarious.
Look carefully. In addition to the cui on a platter, there's a bottle of chicha (Andean Viagara [the local rotgut]) on the table, and the face of Judas (lower right, looking out) is Juan Pizarro.
Next morning at the butt-crack of dawn, we were scheduled to take the train to MachuPICCHu. So as soon as we got back to the Monasterio, we ordered room service, re-packed (you can only take one bag each on the train) and collapsed. Getting to be a habit.