If you're at all interested in the history of classic cocktails. The Old Fashioned is a great place to start. They were created in the very early 1800s, where it was just called the cocktail, and then after a stint of variations well into the 1860s, the cocktail came back in it's original form as The Old Fashioned; a mixture of spirits, bitters, sugar and water.
Note that I said spirits and not rye or bourbon. What's doubly cool is that the old fashioned is amongst the Sour and the Fizz as a recipe which can be applied to nearly any spirit, bitters or variation. Historically the Old-Fashioned has gone from Bourbon, to Rye, to Tequila to Gin. And with a slight stretch of the recipe (swapping sugar for vermouth) you get the Martini and the Manhattan.
The Classic Old Fashioned
2oz Any Spirit
2 Dashes Bitters
1/2oz Simple Syrup (Or stir in a teaspoon of sugar)
Stir over ice and strain into an old fashioned glass filled with a large block of ice. Garnish with an orange twist.
My Old Fashioned recipe is a slight variation of the classic recipe. The ingredients are scaled down slightly (So I don't feel so bad about having two) and I use a slight variation of sugar syrup which came from my misunderstanding the process behind the Bon Apetit Burnt Sugar Old Fashioned.
Toffee Simple Syrup
1/3 cup Raw Sugar
1/3 cup Still Water
Put the sugar in a pot over medium-low heat and intermittently add water. Do not let the sugar burn but it should melt in places. When most of the water is in the pot, scrape any sugar which has clung to the bottom and stir in with a metal spoon.
My Old Fashioned
1 1/2oz Rittenhouse or Sazerac Rye
1/3oz Toffee Simple Syrup
2 dashes Orange bitters
1 dash Angostura bitters
I like to garnish with a twist of orange and, when they are in season, a fresh cherry.