Today, a luxury New York apartment means a glassy tower, a sprawling living room, and ridiculous amenities like an outdoor showers and sky garage, but a century ago? High class living meant a fireproof building, extra servant rooms, and a shared open courtyard. To advertise these buildings, The World's Loose Leaf Album of Apartment Houses was published in 1910, and the New York Public Library has the whole thing digitized. The book pairs exterior photos with original floorplans and a brief description of what makes each building luxurious. Why live in the Chatsworth? "A conservatory has been erected as the mansard story, and is furnished as a sun-parlor for the comfort and convenience of tenants. Extra servant rooms, in the basement, may be rented." Click through for a few tipster-chosen highlights.