1. Prepare the Glass: Fill an old-fashioned or rocks glass with ice cubes to chill it.
2. Mix Ingredients: In a mixing glass, combine the gin, Campari, and sweet vermouth.
3. Stir: Add ice cubes to the mixing glass and stir gently for about 20-30 seconds until well chilled.
4. Strain: Strain the mixture into the prepared glass over the ice cubes.
5. Garnish: Twist the orange peel over the drink to release its oils, then drop it into the glass.

Serve and enjoy!