The landscaped park, which was created on the basis of designs by Peter Joseph Lenné and planted by Fürst von Pückler and John Adey Repton, is an integral part of the castle estate and an important artistic element of its architecture. It replaced the extremely formal 18th century baroque garden. In the course of the renovation of the castle and grounds, the garden designer Adelheid von Schönborn was commissioned with its restoration in the 1990s. The park is justly considered an outstanding element of the Mark Brandenburg's cultural landscape.
As with the renovation of the period buildings, the historic building and monument conservation aspect again dictated that the aesthetic intentions of those who originally designed the building and the landscaped grounds had to be reinstated. The manner in which the spaces had formerly been connected to resemble a painting had to be recreated, always under consideration of nature conservation aspects.
A walk around the park constantly opens up new sight lines in which the castle building, but also other fixed points and prominent landscape design elements, come into view and are emphasised. One of these is the very first monument dedicated to Frederick the Great. The work of art was created by the Luccan sculptor Giuseppe Martini and designed by Johann Wilhelm Meil. It shows Mars, the god of war, and Minerva, the goddess of the arts and sciences, at a column with an urn, in mourning for the deceased king. Joachim Bernhard von Prittwitz had the monument erected in 1792. It was extensively restored in 2012/2013.
In 2004, an independent jury voted the Neuhardenberg Castle grounds 'Germany's most beautiful park' in recognition of the outstanding commitment to the restoration of the original design, the high quality of the restoration and the park's exemplary, meaningful use.