You say you’ve been to Heidelberg, have ridden the cog-wheel train up to the castle or top of the Königstuhl and seen most of the city’s sights?

Although most visitors to Germany are more than familiar with this picturesque town on the Neckar River — home to the U.S. Army Headquarters Europe — many never chance to explore the mountain facing the old-world town. High above the river on the Heiligenberg are remnants of medieval monasteries and a Nazi place of celebration.

Those who may have read novelist Erica Jong’s book “Fear of Flying” will already have encountered this oft-overlooked historical site as she alludes to time spent there while living as a military spouse in Heidelberg.

Visitors can follow in the footsteps of the likes of Mark Twain and Johann Wolfgang Goethe up the Philosophenweg (Philosopher’s Walk) into the forest high above the Neckar or drive around the back of the mountain through the Heidelberg suburb of Handschuhs-heim (cross the Theodor Heuss Bridge), up the Bergstrasse, Mühlentalstrasse and Chaisen-weg to reach the first stopping point — a stone tower built in the 19th century offering a lofty view of Heidelberg and the Neckar River Valley. The tower stands adjacent to a pile of stone blocks which mark the location of the long-ago abandoned St. Stephan’s Monastery.

From the tower one can walk or drive deeper into the forest near the top of the 440-meter-tall Heiligenberg to discover a restaurant with an outdoor garden and the entrance to an expansive amphitheater.

Nazi amphitheater

This Feierstätte or Thingstätte, which today rests grass-covered in the forest, once served as a place of celebration for members of the German National Socialist Party in the 1930s. Built in 1935, it was rarely used by the Nazis.

Continuing up the stone steps through the amphitheater takes one to the top of the Heiligenberg, where ancient monks once worshipped and inhabited St. Michael’s Monastery.

Today one can only imagine what life may have been like high atop a mountain in the Dark Ages while wandering through the reconstructed walls, cellars and foundation of the religious haven built in the 9th century and abandoned in 1503. Signs indicate what the various rooms were used for and two small towers offer views down the back side of the mountain toward Ludwigshafen and the Bergstrasse.

Other signs in the forest indicate that long before the Christian monks populated the Heiligenberg, Celtic settlers laid claim to the area building dwellings and walls as early as 450 B.C.

Visitors young and old will appreciate the solitude and natural setting of the historical sites on the Heiligenberg. Packing a picnic lunch to be eaten while resting on the stone seats of the amphitheater and enjoying an impromptu sing-along to test the outdoor assembly area’s acoustics also makes for an enjoyable family outing.