Heart of one of the world’s leading global cities, Manhattan has its own struggles with keeping brick and mortar retailers in operation:

That’s right: On a nine-block stretch of what’s arguably the world’s most famous avenue, steps south of the bustling Time Warner Center and the planned new Nordstrom department store, lies a shopping wasteland.

Yes, there are bank branches, restaurants, fast-food outlets, theaters, Duane Reades, a vitamin shop and a few tourist-targeted “discount” stores. But mainly there are oodles of empty spaces covered with signs touting SUPERB CORNER RETAIL OPPORTUNITY.

The same crisis blights the rest of Manhattan. The people invested in storefront retailing — real-estate developers, landlords and retail companies themselves — tell us not to worry. It’s a “transitional” situation that will right itself over time. Authoritative-sounding surveys by real-estate and retail companies claim that Manhattan’s overall vacancy is only just 10 percent.

But they are all wrong. Bricks-and-mortar retail is shrinking so swiftly and on such a wide scale, it’s going to require big changes in how we plan our new buildings and our cities — although nobody wants to admit it.

This is an interesting argument to make: even with all of the tourists, wealth, and attention bestowed upon the borough, retail is disappearing from Manhattan. And if shopping disappears, with shopping being one of the favorite leisure activities of Americans, might this negatively affect the business and social life of a Manhattan used to ultra-busy sidewalks?

On the other hand, Manhattan may not be the best example. The median household income in Manhattan is not as high as one might expect, there is not much of a middle class, and the cost of living is high. Add in that Manhattan does have a lot of tourists, workers that arrive for the day and leave at night, and concentrations of residents in different parts of the island. The sheer density of people might suggest that retailers should be able to make it in Manhattan but it is a complicated place.

More broadly, what will tourist locations of the future look like if even more shopping is done online? For decades, the international tourist destination includes significant amounts of shopping. What would fill that space?