About 12,000 years ago, the Neolithic Revolution marked the transition in human history from nomadic hunting and gathering to settling in permanent communities. In all probability, from that time forward mankind has fantasized about a city of the future.

Plato’s Atlantis was the source of inspiration for numerous literary and Utopian concepts, some of which have survived to this day.

Many a child of the Silent Generation can vividly recall watching the 1939 movie “Wizard of Oz” — following Dorothy and the gang along the yellow brick road to the gleaming Emerald City. And how many kids in the 1960s were left wishing they too lived in Orbit City where, like the Jetsons, they could fly to school and have a robot maid.

More recently, we can thank Walt Disney Studios for creating Tomorrowland, a 2015 movie filled with sleek buildings and teeming with robots, jet packs and space ships. The plot merited a barrage of rotten tomatoes but the filmmaker’s vision of what a city of the future might look like certainly fired the imagination.

Fictional renditions of the post-modern metropolis aside, we’ve discovered a number of real-life brick-and-mortar — or rather, glass, steel, ashcrete and carbon fiber — developments that suggest that cities of the future may be nearer at hand than we think.

Songdo, South Korea, is generally recognized as the world’s first smart city. Built on 1,500 acres of reclaimed land near Incheon, it is a low-carbon, eco-friendly, master-planned metropolis that is loaded with technological innovations.

The city’s buildings and streets bristle with sensors that monitor everything from energy use to traffic flow. The district boasts more than 20 million square feet of LEED-certified space, the highest concentration of LEED-certified projects in the world.

Pneumatic tubes send trash from residential units to an underground waste facility where it’s sorted and then recycled or burned for energy generation. Lighting, temperature controls and appliances can be adjusted via a central control panel or remotely from a cellphone. There’s a state-of-the-art water recycling facility and generous swaths of greenery sprinkled throughout — the largest one being the 100-acre seaside park modeled and named after New York City’s Central Park.

Trikala, Greece, may seem an unlikely candidate for a leading smart city, owing to its remote location in the country’s agricultural heartland. Inspired by an innovative, tech-savvy mayor who collaborated with the European Commission and some of the continent’s major tech companies, Trikala has taken a big step into the future.

The most substantial impact on residents’ lives was the digitalization of municipal operations, including an e-complaint system to help speed up services, traffic light monitoring and control, a driverless bus system, and the implementation of robotics labs in the city’s public schools.

A few American communities have made some promising futuristic advances as well.

Thanks to a huge 75 MW solar facility built by Florida Power & Light, the small Florida town of Babcock Ranch, just northeast of Fort Myers, has become the country’s first completely solar-powered community — and the first to introduce a self-driving public shuttle network. The town, with a potential for 50,000 fiber-optically connected residents, was designed and constructed from scratch by developers Kitson & Partners, in coordination with state and local governments.

Emerging from a gritty railyard on Manhattan’s West Side, Hudson Yards is a bold $25 billion development that touts itself as “Tomorrow’s City Today,” and is on its way to becoming the largest real estate development in United States history. This grove of crystalline skyscrapers comprises a mixed-use business, retail and residential complex, encompassing 18 million square feet of built space and about 15 acres of open public space.

Hudson Yards is seen as a cutting-edge model for the future of so-called smart cities, i.e., those with fully integrated infrastructures where internet and communications systems, water services, and electrical and power grids are all connected and unified. Although one critic described it as a “surface spectacle,” big name business (BlackRock, Warner Media, L’Oreal) and retail (Neiman Marcus, Dior, Gucci) have enthusiastically embraced the development.

Apartments and condos are reportedly filling at a rapid clip. A second phase of the project is slated to open in 2025.

Another exciting smart city concept being advanced internationally is Saudi Arabia’s planned Red Sea city of the future, named Neom. A master-planned smart city and tourist destination on the Red Sea coast near the borders of Egypt and Jordan, it is a pet project of controversial Saudi Crown Prince Mohammed bin Salman, who has pledged $500 billion to get the project moving.

Some of that funding is to come from the bounty the kingdom expects from its planned IPO of state-owned Saudi Aramco. That IPO, however, has been delayed until late 2020, so development of Neom could be slowed. Toxicity surrounding the brutal murder of journalist Jamal Khashoggi, widely believed to be at the hands of the prince, has turned off some international investors in the project, but analysts suggest the smell of money will eventually find them back on board.

The Neom initiative emerged from Salman’s Saudi Vision 2030, a plan that aims to reduce Saudi dependency on oil by diversifying its economy and developing its long-neglected tourism industry.

Plans call for robots to perform functions such as security, logistics, home delivery and caregiving — and for the city to be powered solely with wind and solar power. The first phase of Neom Bay Airport was completed in June 2019, and the facility is now capable of handling international air traffic.

Perhaps the most interesting and feasible future city concept comes from no less than (trumpets, please) Google. The search engine giant’s parent company, Alphabet, has tendered a proposal to build a smart city named Quayside on 350 currently unused acres of Toronto’s eastern waterfront.

“Googleville,” as pundits have tagged it, would feature a long list of high-tech amenities such as solar power, geothermal heat, fiber-optics, and wireless 5G internet for everyone. A subterranean network of tunnels would be used for robotic waste collection and walkways and bike lanes would be heated in the winter.

The design relies on a vast range of data collection, including sensors literally everywhere to track things like the speed of people crossing the streets and park bench and restroom usage.

This has raised suspicion among those who distrust large tech companies that Google will use its vast financial resources and surveillance powers to usurp privacy and exert control over the populace. The project is estimated to cost about $3 billion, with Alphabet putting up $900 million. The plan still needs approval from Canadian regulators and the city of Toronto.

Looking a bit farther into the future, we will likely see such seemingly radical concepts as floating cities and self-contained biospheres become realities. If it can be imagined, there’s no doubt it will be built one day.