Complex sentence: The group was founded in 2010 as the US branch of Stop Islamisation of Europe, and has gained some notoriety through highly publicized ad campaigns in New York City, especially one opposing Park 51, a Muslim community center proposed for lower Manhattan.
Split into simpler sentences: The group was founded in 2010 as the US branch of Stop Islamisation of Europe. It gained its notoriety through highly publicized ad campaigns in New York City, especially one opposing Park 51, a Muslim community center proposed for lower Manhattan.