So, um, I tested if it'd be possible to destroy my Portal. Yep. 

Now I've got no portal and no way to actually rebuild it since everyone starts with it and there's no blueprint. Not that it matters much, since evidently I can still send pets to the islands even without it.

But I'm thinking that maybe it shouldn't be possible to destroy the basic buildings that have no blueprints, such as the portal, pound, and first level stable, laboratory & warehouse. ^_^;

Thanks for adding that feature, though: will make the architect award far easier to get. 

Thank you for reporting! You're right, the buildings must be indestructible. This problem is fixed right now, we returned your portal to you :) Sorry for the inconvenience.