I miss the smell of airports when it used to include cigarette smoke. I don't even smoke but I travelled a lot in my younger years and that's what smells nostalgic to me. Also, I smelled a lilac candle in a store once and burst into tears. It transported me right to my grandmother's garden. Smell is the only sense that goes directly to the limbic system, including the amygdala and the hippocampus, the regions related to emotion and memory.