We’ve all heard about smartphones. Now there are smart benches. That is the idea behind a new Boston initiative which will bring “Soofas,” solar-powered benches, to the city. The benches, to be located in various parks, will allow residents to take a load off their feet — while plugging in and recharging their cellphones. “Your cellphone doesn’t just make phone calls, why should our benches just be seats?” Mayor Martin J. Walsh said in a statement Friday. The high-tech benches were invented by MIT Media Lab spinoff Changing Environments, a Verizon Innovation Program. The benches also connect wirelessly, using Verizon’s network, to the Internet to upload location-based environmental information, such as air quality and noise-level data. City officials said the first units in Boston will be funded by Cisco Systems, a leader in development of smart city solutions, at no cost to the city.