Urban expansion, economic growth, and transportation infrastructure exert significant pressures on landscapes, particularly in suburban regions, leading to farmland abandonment and the proliferation of fallow land. These areas, intended as agricultural land left unsown to restore fertility or due to shifting production incentives, represent both an ecological resource and a latent asset within urbanizing territories. Their spatial distribution reflects complex interactions between economic cycles, land-use policies, and speculative pressures of real estate market, highlighting the dual role of fallow land as a ‘buffer zone’ for agricultural activity and as a stock for urban development. Sequential economic downturns influence the dynamics of fallow land, with expansion periods often promoting land withholding for speculation, while downturns enable re-cultivation and intensification of traditional crops. These processes are further shaped by planning regulations, zoning flexibility, and informal land-use practices, contributing to spatial heterogeneity in metropolitan expansion and thus consolidating the entropic distribution of vacant land. Fallow land also plays a critical ecological role, supporting soil conservation, water regulation, biodiversity, and landscape connectivity, while maintaining cultural and agricultural heritage. Effective management of peri-urban landscapes requires integrated, multi-level strategies that consider socioeconomic, environmental, and cultural dimensions together. Recognizing fallow land as a practical example of peri-urban vacant land and, at the same time, as a strategic component of urban–rural interfaces, allows for sustainable land-use planning, balancing agricultural productivity, ecological resilience, and urban containment. This approach provides a framework for understanding and guiding landscape transformations in advanced economies experiencing rapid urbanization, social transformations, and land-use change.