The oldest documented references to Heidelberg Castle are found during the 1600s:* The Thesaurus Pictuarum of the Palatinate church counsel Markus zum Lamb (1559 to 1606);* The "Annales Academici Heidelbergenses" by the Heidelberg librarian and professor Pithopoeus (started in 1587);* The "Originum Palatinarum Commentarius" by Marquard Freher (1599);* The "Teutsche Reyssebuch" by Martin Zeiller (Strasbourg 1632, reprinted in 1674 as the ""Itinerarium Germaniae"").
Od nekem gradu je nazadnje govora leta 1294.