The Negroni!

If you like cocktails, and live in Manhattan in particular, you know the Negroni. Gin, sweet vermouth, and Campari, or some other aperitif. Just about every bar serves them nowadays.
There are various recipes out there. I believe the original was 1:1:1.
Based on today's taste preferences, a reliable go to is:
1.5 oz gin
1 oz aperitif
.75 oz sweet vermouth
1 dash orange bitters
Garnish with orange peel

Stir. Drink. Enjoy.

Cheers.