View of Assmannshausen, Germany, from 1910 book

This is a photo of Assmannshausen, Germany, from the 1910 book:

"The German Rhine
Thirty Picturesque Views of the Rhine¹
including Heidelberg, Wiesbaden and Frankfort.
With interesting Descriptions.
Translated by Andrew Mitchell."
Since 1977, Assmannshausen has officially been a part of the town of Rüdesheim am Rhein. It is famous now for its Assmannshäuser red wine.

Here is some description of what Assmannshausen was like more than a century ago, from the text on the page opposite the photo:

"The little town has not much room for modern expansion. The valley is narrow, and the steep vine-covered slopes rise immediately behind the houses. If we walk along the long promenade however, between the friendly hotels and the broad murmuring floods of the Rhine, we soon begin to enjoy the peace and stillness which broods on the vale. ... The names of several German poets are associated with Assmannshausen. Karl Simrock, Hoffmann von Fallersleben, Emil Rittershaus, and FERDNAND FREILIGRATH have sojourned here. Freiligrath lived in the town for some years. Having been in business in London as a youth, this poet had an intimate acquaintance with the English language and literature, and when in the revolution year 1848, he was obliged to flee from his native land on account of his poems on liberty, it was in the great city on the Thames that he found an asylum."

Also in this photo, on the other side of the Rhine, you can just make out Burg Rheinstein on the side of the bank. The book's author describes the castle as "clinging like a swallow's nest to the side of the steep rock."

But I find the photo's foreground more interesting. What is the story with the metal cross on the left side of the frame? Is it a grave marker? Something else? And is it a Celtic cross?

Footnote
1. Here are two previous Papergreat posts about the Rhine:

• Two stereographic cards from along the Rhine
• Weekend postcards: More Hazelden, the Rhine and the Pa. turnpike