Dyrehavsbakken ("The Deer Pasture's Hill"), commonly referred to as Bakken ("The Hill"), is an amusement park near Klampenborg (Gentofte municipality), but which belongs under Lyngby-Taarbæk Kommune, Denmark, about 10 km north of central Copenhagen.

It opened in 1583 and is the world's oldest operating amusement park. 

With 2.5–2.7 million visitors per year, it is the second most popular attraction in Denmark, after the more widely known Tivoli Gardens amusement park. Unlike Tivoli admission is free.

Bakken may have started as a place to get clean spring water, but today it is a thriving amusement park filled with modern rides and amenities. 

Bakken is home to six roller coasters, the most famous of which is Rutschebanen (Danish for "The Roller Coaster"), a wooden roller coaster open since 1932.  The park is also home to dozens of other amusements and smaller rides suited for all ages.

According to en.wikipedia