This image is of the riverside town of Boppard.

The description on the back translates roughly as follows:
Boppard. Town with 6500 inhabitants, is characterized by a particularly versatile environment and very scenic location on the river. In Boppard flow six lovely streams into the Rhine. It is the starting point of Hunsrückbahn [a now partially abandoned traction railway].
Population is now close to 16,000, 80+ years after this postcard was purchased.
This is number 127 in the series.

This week begins with an illustration of the old Bacharach House instead of the Rhine itself.

The description on the back translates as follows:
The old house in Bacharach is one of the most beautiful gems of old German architecture on the Rhine. The house, dating from the 1368, is of high architectural significance, proved by the fact that it was repaired in 1897 by state and provincial funds.
It is number 122 in the series.
 

The week finishes with a view of the artist’s home town of Assmannshausen.

The description on the back of the card translates (crudely) as:
Assmannshausen with the artist’s home “The Crown” of Bushels, Freiligrath, Geibel. Knight House is famous for its fiery red; directly on the Rhine with a view of Swiss House, Rhinestein and Falkenburg.
It is number 116 in the series.

Here is a sunset view of Cologne, Germany featuring the famous cathedral as seen from the far side of the Rhine.

The description on the back of the card translates roughly to:
Cologne
In the Rhine, in the beautiful river
as Reflected in the waves
with his Big Dome
the Great Holy Cologne.
 
It is number 113 in the series.
 

Here is a view of the romantic ruins of the Godesburg Castle.

The description on the back of the postcard translates as follows:
The Godesburg
The castle dates from the 11th century, was destroyed in 1503, completely devastated. Only the 30m tower beautifies the area and still provides a magnificent panoramic view.
This is number 110 in the series.

This time we see the massive rock along the Rhine known as the Lorelei.

The legend on the back is from a German poem, translated crudely as follows:
The Lorelei
The Lorelei waved from fading Stone,
Performance floods down her veil
And contributes to the listening land into
The gold melting blood of her songs.
She has sung in my lonely hour
Of home and hope and love;
There the words out of her mouth
Remain forever in our hearts.
— From the epic “Trutz Katz” by Jorg Ritzel
This is No. 105 in the series

Next is a view of the “Mouse Tower” a keep in the middle of the Rhine river on a small island.

The description on the back of this card, translated from German:
The Mouse Tower on the Rhine near Bingen received its present form in 1856, but has existed since the mid 13th century. The grisly legend, the scene of which it forms, Rutland tells in his book Tell Rhine. Today the Mouse Tower serves as a signal light for shipping. About Rudesheimer against the mountain we see the glorious ruins of the castle rock.
This is number 103 in the series.

Today I begin an artistic tour of the Rhein river, from art postcards purchased by a relative during a European vacation in 1930. Presumably, all the images date from at latest the 1920’s, but given they are artworks, could be significantly earlier. The physical cards themselves, however, are 1930 era.
The first place is Rheinstein Castle.

The back of the card has a legend in German, translated (poorly) as:
A jewel of the German past is Rheinstein Castle, like the nest of a bird of prey on a narrow, steep cliffs, rising high above the flowing waters of the Rhine.
It is number 93 in the series.