Papal Encyclicals Online is a simply terrific resource where you can find and read an astounding number of documents from the Church’s history.
It’s where I first found and read the Vatican II documents, which I need to reread, but you can find encyclicals going back to 1227 and the documents of all the Church councils. Most of the encyclicals on this site come from the 5 volume set, “The Papal Encyclicals 1740-1981” published by Pierian Press. Not all, however, since they also have current documents including Pope Benedict XVI’s writing.
One of my favorite things about this site is how well organized it is. You can find documents sorted by time period, pope, relevant documents to current issues, and more.
Drop by and browse around. You may be surprised at what you find when you read the documents themselves instead of trusting “what everybody knows.”