Did U know? Isola del Giglio is an Italian island and comune situated in the Tyrrhenian Sea, off the coast of Tuscany, and is part of the Province of Grosseto. The modern island was formed probably 4.5 to 5 million years ago, and has been inhabited since the Stone Age. Later, it was probably an Etruscan military stronghold. Under the Roman dominion, it was an important base in the Tyrrhenian Sea, and was cited briefly by Julius Caesar.