The focus of smart cities has changed. They have become more ambitious as budgets increased to trillions of dollars overall, unaffected by Covid-19. The original concept was based on widespread deployment of information and communications technology ICT such as Internet of Things and 5G. However, in 2020 smart cities have been pivoting reinvented hardware and associated systems. There is a realisation that these may take up to 90% of the investment. That means smart buildings even in the sea and in deserts. Forest City Malaysia will be reclaimed from the sea and be a jungle of self-watering vegetation.Some technologies in future zero-emission smart cities. Source: IDTechEx Research, “Smart Cities Market 2021-2041: Energy, Food, Water, Materials, Transportation Forecasts”, www.IDTechEx.com/SmartCities.It means new forms of transport such as autonomous cars travelling at speed in underground tubes (Elon Musk Loop). Will it be Hyperloop achieving airline speeds in vacuum tubes between cities using magnetic levitation with trains only three seconds apart? Important now is cities making their own food, fresh water and electricity for security and cost reasons. Multipurpose is key. Examples are Toyota robot shuttles replacing many types of city vehicles in its planned Woven City, repurposing through the day. School bus then parcel delivery then taxi? They will go over solar plazas and even into shopping malls. Smart glass will perform many functions together. Aquaponics grows fish and vegetables as food in a single set of tubing, the plants feeding on the fish excrement. Agrivoltaics has the new bifacial solar cells mounted vertically like rows of fences so a small field is both a farm and a power station. Yes, multipurpose and smart materials are important now and IDTechEx forecasts that radically new smart city technology may rise to around $1.7 trillion yearly in 20 years. Republished by arrangement with IDTechEx. Original report Smart Cities Market 2021-2041: Energy, Food, Water, Materials, Transportation Forecasts at www.IDTechEx.com/SmartCities.