The crowds at the opening of Siegel-Cooper department store on September 12, 1896 were so crushing the police had to call in for back up. Eleven thousand pushed inside the doors within just the first ten minutes, and there was a solid wall of people stretching along Sixth Avenue, from 14th to 23rd streets. By the time doors closed at 10:30pm, 150,000 shoppers had been inside.

Siegel-Cooper was the largest retail space in New York, occupying the entire block between 18th and 19th streets on Sixth Avenue. It quickly became a spectacle on a par with museums, theaters, and other cultural attractions. It felt like a small city, with aisles as wide as streets.

Inside, shoppers were greeted by a 10-foot high fountain with a statue of The Republic in marble and gilded bronze- a replica of the one Daniel Chester French had designed for the 1893 Chicago World's Fair.

After dropping their children at a nursery, women could wander through the store's 125 departments on six floors, admiring goods as diverse as canned food, feather boas, live animals, and sheet music. They could then lunch on lamb stew or chicken pot pie in the restaurant and head up to the roof for a view of the city from the observatory. Before picking up their kids—and without ever leaving the building—they could visit the dentist, send a message from the telegraph office or deposit a check at the bank.

Before picking up their kids—and without ever leaving the building—they could visit the dentist, send a message from the telegraph office or deposit a check at the bank.

Department stores, epitomized by Siegel-Cooper, were unlike anything shoppers had experienced before. Over the course of the 19th century there were dramatic changes in what retail stores looked like, what they sold and how they sold it. Before the Civil War, shops mostly specialized in one type of item, such as books, purses, or carpets. Or there were dry goods stores that sold ready-made items, fabrics, and other sewing materials. Window displays and interiors were cluttered and customers went in to negotiate the best price for just the items they needed.

Stores like Siegel-Cooper, A.T. Stewart and Macy's ushered in the era of New York City's department stores—building marble and cast-iron palaces with window displays that lured passersby. They had dozens of departments with ready-made goods from corsets and parasols to furniture and toys.

They had lounges and lunchrooms that fortified customers to stay and buy items on impulse. And throughout the store, scores of shop girls, trained in the art of selling offered merchandise at a fixed price.