A little before the holidays, I was contacted by a 2nd cousin twice removed on the Gillan side of the family. In composing my much-belated response to him, I realized that he had probably come across our ancestors on the 1911 Irish Census when he visited this blog, but that he hadn't found them on the 1901 Irish Census. For some reason, I never posted it, back when I was posting all of the other information about this family.
The household appears on line 14 of Form B1. A glance upward tells me that I need to explore more of the census forms for Tawnykinaff, Co. Mayo, Ireland. There's another Gillen family, a couple Grimes families (Honor's maiden name was Grimes), a few O'Donnells (Martin had a daughter who married an O'Donnell, and her children Nora and Hugh lived with their aunt, Mary Gillen Quinn, in Brooklyn), and some Stauntons (Martin's obituary mentions a Mrs. T. Staunton, his niece).
According to this form, the Gillens had 2 "out-offices and farm steadings." Their house had walls of "stone, brick, or concrete;" a roof of "thatch, wood, or other perishable material;" "2, 3, or 4 rooms;" and 2 windows at the front.
According to the next form, Form B2 (which I'm having trouble downloading at the moment, or I'd include it), the Gillen's two out-buildings are a calf-house and a barn.