From "Greek Isles in the Summer" Magazine

The Citron fruit is from the citrus family, it looks like a giant lemon, which has a very small and very sour juicy part in the middle so it is not worth to be eaten raw as a fruit. It has been known in antiquity as the median apples or in latin Citrus Medica. Today it is grown partly in the Middle East. In Arab countries it used as a replacement for vinegar because it is very acid, also in Persia it is used to flavor fruit salads and for marinating meat. In some places the leaves are used for tea and the fruit is used to make citron oil and citric acid. In Greece (and in the south of Turkey) the fruit is preserved and made into spoon-sweets, marmalades and candies. 

In Greece today the Citrus trees are grown mainly in Naxos island which is a member and the largest islands of the Cyclades group just in the center of the Aegean sea. It is believed that it has been introduced by Alexander the Great and thus it was called the Median Apple from Media, which is the ancient name of Persia and for a very long time it was the only citrus fruit cultivated in Europe.

At Naxos island the leaves were distilled into the Citron liquor which the island of Naxos is famous for. By the late 19th Century Citron was the main export of Naxos to Russia, Austria, France and even the USA. However later lost it's popularity, especially after the second World War when whisky became popular in Europe. 

Up until the sixties the fruit trees were abundant on the island but because the liquor has lost its popularity, the trees began to be replaced by other crops, like maize. The citron trees are still cultivated in the island mostly in Naxos Town, Engares, Halki, Melandes and Apollonas. The tree has purple flowers and large, thick-skinned aromatic fruits. Orchards are within small valleys and are usually surrounded by kalamia (reeds) to protect them from the winds.

For distillation the leaves are collected in October, being careful not to take too many and hurt the tree and are laid out and dampened with water. After that they are placed in a broiler with pure alcohol and water and distilled up to three times, and flavored with sugar. If you crash the leave of the Citron tree between your fingers you will feel their intense and lovely lemon aroma.

Today there are only two producers of Citron Liquor in the whole wide world : Vallindras and Pro mponas. In 1896 Markos Vallindras established the first Naxos distillery in Halki. They have been producing their Citron in the traditional way since then. Their brand once could be found all over the world however today this liquor is so rare that it is not even exported out of the island. The original factory is a museum where you can see how the product is made and sample some for yourself. There is a shop where you can buy any of the three different flavors of the Kitron liquor as it is called: 

• Green : which has more sugar and less alcohol (30%)
• Yellow : medium (35%)
• Clear : which has much alcohol and less sugar (40%)
  So if you ever go to Naxos island be sure to visit the old Vallindras distillery and museum in Halki village, try it and buy as many bottles as you can back home to enjoy it as an aperative drink in the evenings.