Combine the sugar and water in a small saucepan over high heat.
Stir until the sugar has dissolved and the water begins to boil.
Remove from heat and allow to cool.
Wash the lemons, and then use a vegetable peeler to cut long strips of lemon peel, working from the tip to the base. Use a paring knife to gently scrape off any white pith attached to the yellow peel.
In 48-ounce or larger glass container, combine the strips of lemon peel with the vodka. Cover and set in a kitchen cabinet or dark closet to steep for 14-21 days. The longer you let it steep the more intense the color and flavor will become.
Remove the lemon peels from the vodka.
Combine the simple syrup with the lemon-infused vodka and chill. The limoncello is best served ice cold. You can place the limoncello in the freezer for an hour before serving to make sure it is properly chilled.