The power of eminent domain arises as an inherent attribute of sovereignty that is necessary for government to exist. Properly exercised, the eminent domain power effects a compromise between the public good for which private land is taken, and the protection and indemnification of private citizens whose property is taken to advance that public good. The Fifth Amendment of the United States Constitution, made applicable to the states by the Fourteenth Amendment, and California Constitution, article I, section 19 require this protection of private citizens' property. (City of Oakland v. Oakland Raiders (1982) 32 Cal. 3d 60, 64 [183 Cal. Rptr. 673, 646 P.2d 835, 30 A.L.R.4th 1208].) These constitutional provisions restrain the power to condemn in two ways: by requiring (1) a "public use" and (2) payment of "just compensation" for property taken. Despite the broad eminent domain powers of federal and state governments, a municipal corporation can exercise eminent domain power only when expressly authorized by law. (City of Oakland v. Oakland Raiders, supra, 32 Cal. 3d at p. 64; Code Civ. Proc., 1240.020.) "Statutory language defining eminent domain powers is strictly construed and any reasonable doubt concerning the existence of the power is resolved against the entity." (Kenneth Mebane Ranches v. Superior Court (1992) 10 Cal. App. 4th 276, 282-283 [12 Cal. Rptr. 2d 562].) Government Code section 37350.5 grants a broad eminent domain power to a city: "A city may acquire by eminent domain any property necessary to carry out any of its powers or functions." Another Government Code statute, section 50470, specifically grants a city (defined as a "local agency" in Gov. Code, 50230, subd. (a)) the power to acquire property by condemnation for use as an airport. Code of Civil Procedure section 1240.125 also specifically authorizes a local public entity to "acquire property by eminent domain outside its territorial limits for . . . airports . . . if it is authorized to acquire property by eminent domain for the purposes for which the property is to be acquired." Government Code section 50470 states in part: "Whether governed under general laws or charter, a local agency may acquire property by purchase, condemnation, donation, lease, or otherwise for the purposes of this article and may use any real property which it owns or acquires within or without its limits as a site for an airport." Government Code section 6502 authorizes cities, acting together, to exercise their eminent domain powers jointly. Government Code section 6502 states, in relevant part: "If authorized by their legislative or other governing bodies, two or more public agencies by agreement may jointly exercise any power common to the contracting parties . . . . It shall not be necessary that any power common to the contracting parties be exercisable by each such contracting party with respect to the geographical area in which such power is to be jointly exercised." Government Code section 6500 defines cities as public agencies.