I am quoting from the Return of Sherlock Holmes, The Six Napoleons, by Arthur Conan Doyle:
In half an hour we had reached Pitt Street, a quiet little backwater just beside one of the briskest currents of London life. No. 131 was one of a row, all flat-chested, respectable, and most unromantic dwellings. As we drove up we found the railings in front of the house lined by a curious crowd. Holmes whistled.
So what do 'flat-chested' and 'unromantic' mean when speaking of a house?