My favorite building in New York is slowly fading from view.

Increasingly crowded by unsympathetic neighbors, the Woolworth Building in downtown Manhattan is getting harder to see from a distance. Unlike the era when its iconic structure defined a nascent skyline, from many angles today you can only spot it peeping between taller structures. One of the best close-up views, however, can still be seen from City Hall Park, where you can appreciate one of New York’s defining architectural achievements.

Officially opened to great réclame on April 24, 1913, when President Woodrow Wilson turned on the building’s lights remotely by pushing a button in Washington, D.C., the Woolworth Building was christened the “Cathedral of Commerce” by The New York Times only three days later, thanks to its strong resemblance to European Gothic churches.

I’ve admired this building from afar for decades, but only close up could I truly appreciate the genius behind architect Cass Gilbert’s design. Originally planned to rise 420′, the Woolworth Building ultimately topped out at 792′, employing 23,000 tons of steel covered in 7,500 tons of glazed terra cotta on the façade as well as 40,000 square feet of gold foil at the top. From street level, your eyes travel up the 57 stories of strongly articulated piers, past some of the 5,000 windows, to the turrets, pyramidical roof, and an observation deck that closed in 1941 because the U.S. Navy said the view was too good and didn’t want any visitor making unobstructed observations of its maneuvers around New York Harbor during wartime.

Closer to earth, you can easily appreciate the finer details on the bottom three stories—the European Gothic church elements such as lacy decorations dripping around arched windows and a captivating display of grotesques. All of that primed me to finally explore the interior, which now requires reserving a spot on a guided tour: Access has been restricted for a while, following both tighter security measures after 9/11 (the top of the building suffered collateral damage from falling debris of the Twin Towers) and the more recent transition of the 30 upper floors from office space to private luxury condominiums that range from almost $4 million for a one-bedroom apartment, to more than $26 million for a gorgeous four-bedroom apartment with two generous terraces, to the astounding $110 million penthouse (which, incidentally, includes that old observation deck as its own private outdoor space). Not bad for a building conceived of by the owner of a chain of nickel and dime stores.

When F.W. Woolworth’s first general store opened and promptly tanked, I imagine it would have been difficult for him to give any credence to his mother’s prediction that one day he’d be a rich man. That prophecy probably seemed even more bitter after his five-cent store in Utica, New York, opened in 1878 and failed a few weeks later. Despite these inauspicious setbacks, he persevered and opened a second store the following year in Lancaster, Pennsylvania, and included 10-cent items as well. That fared better, and by 1911 the F.W. Woolworth Company was incorporated with 586 five-and-dime stores. His mother’s prediction had come true, and Woolworth was ready to promote his success by hiring famed architect Cass Gilbert to construct the world’s tallest building as his corporate headquarters—and paying all $13.5 million of its costs in cash, with no loans from banks or developers.

Once you get past the glorious exterior of this building that has been a National Historic Landmark since 1966 and a New York City landmark since 1983 and the guide leads you inside, that price tag—and the Gothic cathedral reference—become even more obvious. Inevitably, members of your tour group will gasp and utter exclamations of wonderment, and with good reason, as if they’ve just entered a 1500s cathedral in France or Germany. The cruciform lobby is simply dazzling. Covered in veined marble from Greece, the ornate lobby features a soaring barrel-vaulted ceiling slathered in vibrant gold, green, purple, red, and blue mosaics of Byzantine floral and abstract designs, and the occasional exotic bird. The stained-glass ceiling light above is ringed with the names of a dozen commercial countries, a series of Ws, and, in the corners, the years 1879 (when the Woolworth Company was founded) and 1913 (the building’s birth year).

Two murals by a German immigrant artist adorn the lunettes above the balconies on the mezzanine level. Labor features a central female, seated and wearing a crown, while two boys kneel down and proffer up grain and fruit. Commerce also represents a female figure, this one holding a globe; the two boys here hold a locomotive and a clipper ship—key commercial modes of transportation of the era.

Amid all the grandeur, I also spied some whimsical flourishes. I found some bronze salamanders, amphibians that were once believed to be able to survive fire, a nod to the building’s “thoroughly fireproof construction” of steel and fireproof terra cotta. Marble corbel sculptures take the form of Cass Gilbert holding a model of the building, Mr. Woolworth counting nickels, and the building’s engineer taking a girder’s measurements. The small mascarons all around you present a series of unique faces—some happy, some with positively awful dental work, some appearing utterly miserable; the ones above the elevator banks are winged.

The Woolworth Company originally occupied only a floor and a half of the building’s space; the remainder was rented to other companies, including Columbia Records and, later on, the Kellex Corporation—“Kell” as a reference to its parent, M.W. Kellogg Company, and “X” for secret: Kellex was part of the Manhattan Project to develop nuclear weapons during World War II. Those tenants must have relished their good fortune: The Woolworth Building featured high-speed elevators (both local and express), a shopping arcade, a health club complete with swimming pool, a barber shop, a restaurant, and a social club. Grand staircases led down to a private entrance to the subway, making it unnecessary for workers to go outside in inclement weather to begin or end their daily commute, as well as a massive vault that would have confounded the most clever burglar. Woolworth remained the landlord, earning handsome rents, until 1998, when it sold the building for $155 million, paving the way for its new life as both office suites and luxury housing.

In our postmodern world, you can rest assured you’ll never see a building of this grand magnitude again. Book your tour today and relive a bygone era of splendor!