Johan Hedenborg (1786-1865) was a medical doctor whose curiosity gave him a wide range of interests in natural and social sciences. In 1825, he was attached to the embassy of Sweden and Norway to the Sublime Porte. After exploring the Aegean and both sides of the Red Sea for fifteen years, he settled in Rhodes with the aim of writing a history of the island. The manuscript, completed in 1857, was never published. It contains copies of 303 inscriptions on stone, 54 of them otherwise unknown, and drawings of more than 150 stamped amphora handles and tiles. All these documents are studied here.