Preparation:
Peel the lemons, being careful not to peel the white part of the skin (which would give them a bitter taste). Cut the peeled lemons into wedges and put them with the alcohol into a wide-necked bottle. Close tightly and let rest in a dark room for 20 days.
After 20 days, prepare a pot with a liter of water and the sugar. Warm the water slightly to allow the sugar to dissolve. Pour the alcohol into the water-sugar mixture, filtering out the lemon skin with the fine sieve. Stir for few minutes and pour into clean bottles quickly so the alcohol will not evaporate. Let the bottles rest in a dark room for another 20 days. After the 20 days, put the bottles in the refrigerator and serve when cold. Limoncello will keep in the refrigerator, if in a sealed container, indefinitely.