Best Urban Block in South Florida? It’s out there.

As towns and cities seek to retool their downtowns and urban districts to lure new businesses and residents, the time seems ripe for a refresher on what makes a good city block — what it might look like, what the key ingredients are, how it ought to function and feel. That refresher is especially needed now because over the years suburban-style development and zoning invaded, and sometimes sped the devastation of, our urban cores.

We’re talking about strip malls with parking lots fronting streets redesigned as highways, impractically narrow sidewalks, yawning parking garage bays on main streets, and lots of blank walls — stuff that doesn’t make good urban places.

Giving exposure to great blocks can also provide a proven model as sprawling suburban communities increasingly try to retrofit to create the pedestrian-oriented urban centers they never had.

And what better place to look for examples than right at home? Although South Florida development took off with the car and the air conditioner, and the region has become synonymous with suburban sprawl, its main cities and original suburbs predate that, and their cores were designed on a traditional, dense city grid.

That means that wonderful, walkable, steeped-in-South-Florida blocks abound if you know where to go. Some have recently found new life. Others never faded. We don’t want to exert undue influence by pointing them out. But many are hardly a secret.

We’re also hoping readers can uncover some great blocks that may be overlooked.

So we are soliciting photographs and short videos of your favorite urban block in Miami-Dade, Broward or Palm Beach counties, accompanied by a brief explanation of why it’s the best. Entries will be judged by five eminent, expert jurors. The winner will get a block party. Individuals will get cash prizes for best photo and video presentations.

What will the judges look for?

A street, one-block long, fronted by buildings on either side. The buildings could also front a plaza, a small park or square, or a pedestrian-only passageway.

The block can be anywhere — downtown, outlying neighborhood, or suburban town center — and it can be old, restored or brand-spanking new.

One thing they’re not looking for: your beautiful suburban block of single-family homes (that’s a contest for another day).

There are several critical ingredients for a great block. The best block won’t necessarily have all of them, but it should possess at least some.

First and foremost is people. The block must be dense and pedestrian-centered, with buildings, streets and sidewalks oriented primarily to accommodating the gathering and movement of people, not cars.

“To me, the clearest criteria, when it’s a true urban block, has to do with walkability. It has to be well-integrated and also appealing,’’ said Miami Planning Director Francisco Garcia, charged with implementing the city’s new Miami 21 zoning code, which mandates pedestrian-friendly development. “It’s very difficult to convey to people in South Florida that development of this sort is what we’re after.’’

The best city blocks also have a mix of uses: shops, restaurants, offices and residences at a density high enough to create a critical mass of activity that draws other people, creates a sense of security and can support commerce. That could mean apartments over the store, or live-work lofts, or any number of varied arrangements, so long as they’re seamlessly woven into the block.

A winning block would also have building fronts and fixtures designed to the human scale and, ideally, good attention to architectural detail. There should be variation in building facades, yet those should be aligned in a consistent “street wall,’’ with lots of transparent windows and doors that open onto the sidewalk and allow those outside to see what’s inside, and vice-versa.

There should also be chances for social interaction, casual encounters and exchanges. That means broad sidewalks, perhaps also street benches, sidewalk cafes or a food stand.

Yes, there can be on-street parking. Some experts say that’s desirable as it shields pedestrians from moving traffic and creates a sense of safety. But not so parking lots or open street-level garages.

Because it’s Florida, shade is good, whether from trees, arcades, awnings or overhanging balconies or ledges.

The block could also have accommodation for bicycles, through bike lanes, sharrows and places to lock up securely, and maybe a trolley or transit stop.

“A great block … has many ways to get to it by foot, by bike, car, bus and rail and even by boat, especially in South Florida,’’ said West Palm Beach architect and Best Block juror Rick Gonzalez.

Another good ingredient is variety, whether in the scale or age of buildings. The architectural style doesn’t matter: 1920s Mediterranean, 1950s MiMo, throwback architecture or thoroughly

“Not all great streets are the same,’’ said Coral Gables-based planner and Best Block juror Victor Dover.

Building heights don’t necessarily matter, either. Great blocks can be found from Times Square on one extreme to the modest scale of New Orleans’ French Quarter or Key West’s Duval Street.

Many urban designers like Gonzalez believe a moderate to mid-rise scale is best. In his experience, he said, what works best are building lots from 50 feet to 150 feet wide, and buildings of two to 10 stories, with a variety of businesses on the ground floor like cafes and shops, and on the upper floors offices or residences, including hotels.

“A great block would be one that all of us would like to live, work, play and learn on,’’ Gonzalez said.

But it’s not inconceivable that a great block could be found in a skyscraper district, if built with an orientation to the street at the base, like in many sections of Manhattan. Some experts say pedestrians hardly notice anything beyond four or five stories above their heads.