If the logic of markets is that price equals value, sometimes there are forms of value that fall outside of what markets are able to recognize. We call this phenomenon market failure. It is not a personal or institutional failure or even a failure of economic theory, just a limitation of markets as a medium. Our core case study is of the opening of Tate Modern. The museum revitalized the Southwark area of London and increased property values sometimes 500%. The museum relied on philanthropy and government support and was not able to capture all of the value it created. We consider two very different methods economists use to evaluate these situations: contingent valuation method and economic development study. We compare and contrast the approaches taken by the Guggenheim and the Tate. We explore concepts of market failure including public goods, externalities, tragedy of the commons, free-rider problems, adverse selection, and moral hazard.