Recent DIY trends show makers increasingly turning to ESP32 microcontrollers and Arduino platforms for smart home projects, replacing costlier or overpowered setups like Raspberry Pi in many cases.

For residents of European cities—with their snarled traffic, drafty old buildings, creaking public services and gray winters—it's easy to see the appeal of moving to a brand-new, high-tech metropolis.

Smart city innovation is accelerating—so fast, in fact, that distant visions of the future are now becoming present-day realities, transforming how communities live, work and play. At the heart of ...