This is a coal-burning L1s 2-8-2 steam locomotive built in 1916 by Baldwin Locomotive Works. It is on display at the Railroad Museum of Pennsylvania in the town of Strasburg.

Info. from rgusrail.com: "# 520 is one of two hundred and five Mikado type locomotives (2-8-2) built by Baldwin for the Pennsylvania Railroad between 1914 and 1916. Three hundred and forty-four were also built at the Pennsylvania Railroad's Juniata Shops and twenty-five by Alco. They were the largest 2-8-2s ever built.

1. 520 weighs 315,000 pounds, 238,000 pounds on its 62-inch drivers. With 27 inche by 30 inch cylinders, a 70 square feet grate, 301.5 square feet firebox, and total heating surface of 5,189 square feet, including 1,154 square feet superheating, it operated at 205 pounds per square inch, delivering 61,465 pounds of tractive effort.

The success of the L1s was soon eclipsed by Pennsylvania Railroad's larger and more powerful I1s/I1sa 2-10-0 Decapods, the largest to operate in the U.S., which began to enter service in 1916. Many L1s went into storage during the Depression and only returned to service with the arrival of World War II.

1. 520 served until nearly the end of Pennsylvania Railroad steam operations and hauled one of the last steam passenger trains on the system, a railfan special between Enola Yard in East Pennsboro Township and Northumberland, Pennsylvania. It was then added to Pennsylvania Railroad's historic collection in Northumberland."