The article discusses World Heritage Site Guanajuato, Mexico, a mature destination which suffers sustainability issues concerning water provision, traffic congestion, and refuse collection, the result of chaotic urban growth. Stagnating visitor numbers indicates ageing social infrastructure, dated tourism products, and reputational damage of public insecurity. The research objective is to improve municipal planning by using a resilience framework from the tourism ecology literature to encourage sustainable development. It integrates the results of a 2021 survey of local tourism business opinion and finds Guanajuato’s multi-business owners are innovative in crisis, reacting to covid-19 with changes to their products and services. Federal and State government hardly responded. It should widen membership of the municipal Tourist Board and incorporate project evaluators within the local Planning Office to apply a resilience model to address environmental, infrastructural, and tourism challenges.