For me it has to be without a shadow of a doubt the spanish revolution arranged by the cnt-fai syndicate. one of the most influential moments and one of the main reasons of why im a libertarian socialist today. the tale of 10 million+ people co-existing in an anarchist society free of coercion and hierarchy is nothing short of inspirtational
"The Spanish Revolution was a workers' social revolution that began during the outbreak of the Spanish Civil War in 1936 and resulted in the widespread implementation of anarchist and more broadly socialist organizational principles throughout various portions of the country for two to three years, primarily Catalonia, Aragon, Andalusia, and parts of the Levante. Much of Spain's economy was put under worker control; in anarchist strongholds like Catalonia, the figure was as high as 75%, but lower in areas with heavy Communist Party influence, as the Soviet-allied party actively resisted attempts at collectivization enactment. Factories were run through worker committees, agrarian areas became collectivised and run as libertarian communes. Even places like hotels, barber shops, and restaurants were collectivized and managed by their workers. Sam Dolgoff estimated that over 10 million people participated directly or at least indirectly in the Spanish Revolution[1], which he claimed "came closer to realizing the ideal of the free stateless society on a vast scale than any other revolution in history
The collectivization effort was primarily orchestrated by the rank-and-file members of the Confederación Nacional del Trabajo (CNT; English: National Confederation of Labor) and the Federación Anarquista Ibérica (FAI; English: Iberian Anarchist Federation), with the two often abbreviated as CNT-FAI due to the affinity between the two organizations and the major role of the latter within the former in maintaining anarchist "purity." The non-anarchist socialist Unión General de Trabajadores (UGT; English: General Union of Workers) also participated in the implementation of collectivization, albeit to a far lesser degree."
http://en.wikipedia.org/wiki/Spanish_Revolution
here's a very quick and informative video on it
[video=youtube;VUig0lFHDDw]http://www.youtube.com/watch?v=VUig0lFHDDw[/video]