This book explores the overlooked role of smell in architecture, design, and urban life, positioning olfaction as a powerful medium for shaping place, atmosphere, and experience. Beginning with the concept of the "scentsphere," it establishes how smells carry cultural memory, therapeutic potential, and behavioural influence, reframing them as active agents in how environments are felt and understood. Building on this foundation, the text introduces a framework for creating smell-spatial narratives, a step-by-step manifesto for creatives to integrate smells into their spatial practices. Smells are conceptualised as spatial design materials and it shifts the paradigm of smells from the intangible to the tangible with new concepts of "scentability," "scentography," and "scentonics." Case studies from art, architecture, and urban design illustrate practical interventions, from scented materials to landscapes and devices, showing how olfactory design operates across scales and durations. Concluding with a futurist outlook, the book situates smellscape ecology within climate change and inclusive, life-centred design, introducing "olfactory diversity" as a guiding principle. This book is essential reading for spatial designers in interior architecture and design, architecture, stage design, situated practice, art practice, curation, event design and management.