Sometimes the ghosts of New York City put clues about Gotham's past right under your nose.

That's what happened on a recent walk down busy 125th Street, between Seventh and Lenox Avenues. On an empty building partially hidden behind scaffolding and a blue tarp are two letters, entwined like a logo: KC.

The initials can be seen from the sidewalk, and they pose the question: What's KC?

Turns out these initials stand for Koch & Co., a once-heralded department store with its roots in the city's Gilded Age, when mass consumerism was born and the idea of shopping for leisure took hold.

Henry C.F. Koch, an immigrant from Germany, founded his eponymous emporium with his father-in-law in 1860, according to Walter Grutchfield. Their first store opened at Carmine and Bleecker Streets, then made the jump the Sixth Avenue and 20th Street in 1875.

At the time, the Sixth Avenue location put Koch & Co. squarely in New York's burgeoning Ladies Mile Shopping District, which roughly spanned Broadway to Sixth Avenue and 10th Street to 23rd Street.

Koch & Co.'s competition on Ladies Mile would have been B. Altman's on Sixth and 19th Street, Hugh O'Neill & Co. on Sixth and 21st, and Macy's at Sixth and 14th Street. These and other department stores sold everything from fashion to furniture to food to women who were free to browse and buy without being accompanied by male escort, as was the usual custom at the time.

In 1892, perhaps taking note of population shifts and the elevated railroads that opened uptown Manhattan to residential development, Koch relocated his store to a new building at 125th Street.

"At that time the street was residential in nature, and H. C. F. Koch & Co. were pioneers in leading the changes that converted 125th St. into a shopping street," Grutchfield wrote.

Koch & Co. certainly got good press. In a New York Times article from 1893, a reporter wrote: "The great store of H.C.F. Koch Co. in One Hundred and Twenty-fifth Street, between Lenox and Seventh Avenues, is, par excellence, the emporium of the far uptown district, and consequently the announcement of its Fall opening is attracting thousands of buyers and seekers after the styles of the season."

Still, it may have been hard at first to lure shoppers so far uptown, as this ad in The New York Times (above) from 1893 hints. Koch himself had moved to Lenox Avenue, and in 1900 he died, passing the business to his sons.

The department store continued until 1930, when it was bought out and closed. The stately building remains, with those CK initials and the name "Koch and Co" carved in stone high above the cornice.

[Third image: NYPL, 1936; fourth image: King's Views of New York City, 1903; fifth image: New York Times, 1893]