Ground-floor

They were shewn into a back sitting-room on the ground-floor, where a certain air of elegant untidiness denoted the lady-like superiority of Mrs. Smallwood.

Source: wiktionary

One day that he had been writing a letter in Mr. Smalls' rooms, which were on the ground-floor, Verdant congratulated himself that his own rooms were on the third floor, and were thus removed from the possibility of his friends, when he had sported his oak, being able to get through his window to "chaff" him; but he soon discovered that rooms upstairs had also objectionable points in their private character, and were not altogether such eligible apartments as he had at first anticipated.

Source: wiktionary

The fact, however, of the porte-cochère taking up so much of the ground-floor is often most ingeniously compensated by making the space to the right or left of the doorway, as the case may be, into an excellent shop.

Source: wiktionary