The queen of all lemons is widely reckoned to be the Amalfi - and a specific variety called the sfusato. It's grown on rocky terraces clinging to a hillside south of Naples.
The lemon is thought to have originated in India - although we now associate it with the Mediterranean and particularly Italy. Frescoes depicting the fruit were found in Pompeii and there's also a mosaic pavement at Frascati from the year 100 AD.
Simon Parkes went to Amalfi to discover the various uses and the history of the fruit.