Both Uses of

alcove
in
Main Street, by Sinclair Lewis

The room beyond, looking on Main Street, was business-office, consulting-room, operating-room, and, in an alcove, bacteriological and chemical laboratory.†
Chpt 15 *

She asserted, "This silly lobby is too florid," and simultaneously she admired it: the onyx columns with gilt capitals, the crown-embroidered velvet curtains at the restaurant door, the silk-roped alcove where pretty girls perpetually waited for mysterious men, the two-pound boxes of candy and the variety of magazines at the news-stand.†
Chpt 17

Definition:

a recessed or secluded space -- such as in a room or garden

The alcove of a room is a smaller room attached to a larger room and separated by an arch or other architectural feature other than a door.