Sustainable Development Goal 11 (SDG 11) focuses on making cities and communities inclusive, safe, resilient, and sustainable, encompassing urban areas, towns, and broader human settlements. Sustainability in this context includes promoting economic growth, social inclusion, environmental protection, and disaster resilience. Key initiatives involve ensuring adequate housing and basic services, providing accessible public transport, fostering inclusive urban planning, and reducing environmental impacts. The least sustainable cities are mainly in developing regions like sub-Saharan Africa, South Asia, and parts of Latin America. Cities such as Lagos, Karachi, and New Delhi exhibit high urban unsustainability, characterized by significant slum populations, inadequate access to basic services, poor public transport, and severe pollution. Residents in these areas face considerable hardships, with many living in overcrowded conditions without secure tenure. Their survival strategies include reliance on informal employment, community aid networks, and informal services for essentials. Additionally, migration for better opportunities and adaptation to unreliable transport options are common. These coping mechanisms only provide limited relief, illustrating the ongoing challenges faced by those in the world’s most unsustainable urban environments.