These organizations develop the land so that it is "shovel ready" for big business, by improving the infrastructure (roads, utilities, landscape, and hydrology).
These sites are typically created close to pre-existing transportation infrastructure (interstates, railroads, intermodal ports, airports, and rivers) and public utilities (electricity, substations, Three-phase electric power, natural gas, water, sewage, fixed-line, and Broadband internet services from Coaxial cable to fiber-optic and Mobile broadband).
It's also located close to human capital such as large populations, universities, or trade schools.
CenterPoint Properties, Eastman Business Park, and Denver Tech Center are examples of private Mega-Sites.
Military bases are secessioned from the state, hence they don't have to pay sales taxes at the exchanges.