The 15-min city model provides a transformative urban framework addressing critical global challenges such as climate change, social inequality, and geopolitical tensions. Centered on principles of proximity and accessibility, it aims to enhance high-quality societal life (HQSL) by ensuring residents can access work, education, health, and leisure within a 15-min walk or bike ride. Emerging from historical debates on urban planning and critiques of car-centric urbanism, the model represents a return to human-centered urbanism. Initially pioneered in Paris, it has inspired a global movement, with cities across all continents adapting the concept to their unique contexts. Its implementation has mobilized a diverse international ecosystem, demonstrating measurable benefits such as reduced carbon emissions, strengthened community connections, and the revitalization of local economies. Underpinned by rigorous quantitative and qualitative methodologies, the model identifies and addresses specific project goals while fostering the global collaboration embodied by the Global Observatory of Sustainable Proximities. However, its implementation faces challenges, including resistance to change, funding constraints, and the threat of gentrification. Overcoming these requires inclusive, participatory strategies and long-term planning. The 15-min city represents a paradigm shift, urging policymakers, urban planners, and citizens to adopt sustainable proximity as the foundation for resilient, inclusive, and livable cities worldwide.