On page 133 of Art and Academe there is a creo terram ritual to create an entire Cathedral (although with consideration of the Aesthetic quality rules on the previous page it will be an ugly one). My issue is that the target is individual. My understanding is that because of the many components of the cathedral it should be target group.
This would mean that the spell would need one few magnitudes for increased size but two more magnitudes for the greater target category for a final level of 50.
Am I right on this, or should a cathedral be considered an individual?
(and before some one chimes in that it should be target structure I will remind everyone about the "targets and creo" box in the spells chapter of the core book.)
Not quite ... Structure affects every target within a given Structure, e.g. every window within the cathedral. But to create the Structure itself, the target is Individual (most likely with a Size modifier). Conjuring the Mystic Tower is the premier example.
Stone and Glass still have Base 03 to create , though i agree they are not the same thing to be used in one spell.
A separate spell to conjure the windows perhaps.
But even there , a single stained glass window need not be many small pieces , joined together.
The CrTe spell creates a single piece of glass with an 'elaborate design' on it , that looks like one.
Still , a Group Target for creating the windows and +02/+03 Complexity for creating a number of different designs.
The Armillary Sphere (page 52 , TMRE) uses two similar spells to either Duplicate or Craft.
Both have an Intellego requisite.
Confusingly , the Craft spell includes +02 for finesse as well as a Finesse Roll vs Ease Factor of 18.
The Duplicate spell includes just the +02 for finesse.
Finesse being used for precision in either spell.
Part of the reason stained glass window are made of so many different pieces of glass is that medieval technology simply could not create large pane of glass strong enough to use as windows. So there is a potential issue of you trying to create something you have never seen. Still, that's nitpicking, at worse you add one magnitude for the lead to bind the pieces. Or you commission the windows separately (after all, you also need bells, pews, an altar, candlesticks, and what not before your cathedral can serve).
As for the initial question, if the spell as an Individual Target, then it is one (elaborately shaped) piece of a single stone, in the shape of a cathedral. no glass, no mosaic, no doors, no bells, and so forth. It sill needs a few month of finishing. A Group Target can add at least some of the missing pieces.
It's still fundamentally a single entity called a cathedral. If you CrAn a cat it's going to be made up of blood, bones, fur, etc. but it's still fundamentally an individual cat. I would say the same applies for individual buildings.