Ancient writings on stone and papyrus are an important source for our knowledge of the classical world. Texts of this sort are, unfortunately, often not translated--though you will find translations of significant texts in sourcebooks.
Finding Primary Sources
Two places to start are
A range of sourcebooks for different aspects of ancient history are available at the Olin Library covering specific historical periods and topics. To find more use the advanced catalog search and add the keyword "sources" to your search terms.