I'm interested in the feelings of being in crowds - the sense of belonging. The vertiginous sense that all control will be lost. It's been many years since I read Canetti on this topic but he's always worth a read. His memoirs: The Tongue Set Free (1977), The Torch in My Ear (1980), The Play of the Eyes" (1985) and the novel Auto-da-Fé (1935), are also worth a visit.