Today is National Cheesesteak Day!

(CNN, KYMA/KECY) - The city of Philadelphia is home to many things like the Liberty Bell, Independence Hall, and of course those celebrated stairs that Rocky Balboa runs up outside the city's Museum of Art.

But Philadelphia is also famous for creating the cheesesteak, a popular sandwich sold across the country, and Monday marks National Cheesesteak Day!

If you never tried one, the ingredients are very simple.

It's a hoagie roll filled with thinly sliced beef, melted cheese, and people often put onions on that sandwich.

The cheesesteak has been a delicacy since 1930 when a hot dog vendor from Philadelphia came up with that idea.