This is an illustration of the ruined 12th Century tower called Der Drachenfels, or Dragon Rock, along the Rhine near Siebengebirge, Germany.

The description is in German, and translates roughly:
The boldest of all the ruins, which are reflected in the beautiful Rhine stream, is the Drachenfels, the proud guardian of the Seven Hills. The size and power of the formation surpassed all the other rocks on the Rhine. The mountain is 325 meters high, the castle was begun in 1117 and quickly called Drachenburg.
–The postcard was collected during a tour of Germany in 1930, so likely dates from just before then.

This illustration shows a scene from an opera as performed and spectated by dogs. It is presumed to be an opera because of the presence of the orchestra playing during the performance.

There is no description on the back of this card.
For simplicities sake, the artist has drawn most of the orchestra, and likewise most of the audience, with nearly the same ‘breed’ of dog, allowing only small variations. It is not clear if the dog off stage is a director or prompter, but it is not a performer as the costume is unlike the other performers.
This image likely dates from the 1940s.

This illustration shows a typical family portrait session with an old bellows camera, but with dogs in the place of people.

There is no description on the back of this card.
Again in this image, the dog photographer has no pants, though the ‘father’ dog does, consistent with the rest of his formal attire. This ‘father’ dog also appears to have hands instead of paws, judging by the way they have been drawn next to the infant dog on his lap.
This card likely dates from the 1940s.

Continuing with the theme from the previous posting, this image shows a collection of various breeds of dog in at a butcher shop operated by large bulldogs.

There is no description on the back of this card.
There are a few interesting oddities in this image as well. The dog customers all have paws, but the butcher dog on the right clearly has hands. In addition, he towers over a trio of what appear to be very small bulldog customers. And, while the ‘female’ dogs have skirts, the ‘male’ dogs have no pants.
This image likely dates from the 1940s.

The postcard tour of the Rhine river concludes with another view of the Lorelei rock.

The description is again an excerpt from a poem, crudely translated as follows:
The Loreley waved from treacherous rock –
Power flooded down her veil
And contributes to the listening land into
The gold flowers enamel of their songs.
She has sung in my lonely hour
Of home and hope and love –
There are the words out of her mouth
Forever remain in our hearts.
From the epic “Defiance Cat” by Jörg Ritzel
It is number 136 in the series.

The last stop for the week is the island castle called Pfalz, or Palatinate.

The description translates as follows:
The Palatinate, situated in the Rhine at Kaub, a highly original building, whose main pentagonal tower dates from the middle of the 11th Century. The little castle was built for the purpose of revenue collection.
—
Presumably, this location made it easy for tax collectors to intercept commercial boat traffic on the Rhine.
This is number 133 in the series.
 

In contrast to the previous posting, this is an illustration of the Castle Mouse. Similarly to the previous post, the actual subject is dimly viewed on a hill in the background while the foreground town takes pride of place.

The description on the back translates as follows:
Castle Mouse was built by the bishop Bohemond of Trier to protect his possessions on the Rhine in 1357. The castle is still well preserved and inhabited occasionally.
It is number 130 in the series.

This picture is a little confusing. Even though the emphasis is on the riverfront and the church, the description talks about the structure on the hill in the upper background.

The description on the back translates as follows:
Castle Cat
Wall and towers, floating high above,
The main boldly lifting into the clouds,
Catle Cat looks proud to rich country,
She has to citizen use and profit
Adopted the royal residence here
On vine-wreathed Fensenwald.
— From the epic “Defiance-Cat” by Jörg Ritzel
This is number 129 in the series.
 
 

This is a rather ostentatious monument to the man who ruled over Germany in the latter half of the 19th Century.  Though it is called the Kaiser Wilhelm Monument, there are several hundred such monuments of various types dedicated to him.

Too bad his son wasn’t a particularly good leader or military commander, since it meant the end of the monarchy in Germany along with the destruction of its empire. The text on the back of the card translates as:
The Kaiser Wilhelm Monument at the German Corner, located at the confluence of the Rhine and Mosel, is one of the buildings that was built in honor of Emperor Wilhelm 1 of Germany. Two Berlin artists are its builders: Professor Bruno Schmidtz and the sculptor Professor Hundrieser. The monument was inaugurated in 1897.
It is number 128 in the series.