Complex sentence: In many ways it functioned as the capital of American Polonia with the headquarters for almost every major Polish organization in the United States clustered within its vicinity beginning with the Polish National Alliance to the Polish Daily News.
Split into simpler sentences: In many ways it functioned as the capital of the American Polonia with the headquarters for almost every major Polish organization in the United States clustered within its vicinity. Organisations located within its vicinity include the Polish National Alliance to the Polish Daily News.