In regards to the other sites where only a portion of a building is inscribed I think we may be able to get the minimum for an connection purely from Spain.
First off the Monuments of Oviedo and the Kingdom of the Asturias, only the Camara Santa of Oviedo cathedral is inscribed.
I thought the same was true of the Mudejar Architecture of Aragon, I thought only the side walls of la seo cathedral in Zaragoza were inscribed, but it turns out it is the whole thing. Although only the tower of San Martin church in Teruel is inscribed, so I guess that fits the bill.
I think there will be quite a few more, and I'm sure I've visited several, they just aren't coming to mind.