Heidelberg
Right, Romanesque, Gothic, with a touch of Baroque, side by side in the great courtyard.  Some might argue with my definitions there, and this is fine as I'm not an expert in architectural design and eras.  Nevertheless, a clear design distinction can be seen between the old (left) and the relatively new (right). 

These photos were taken in 2007.
Heidelberg has a good combination of old and new architecture to be of real interest.  Moreover, the nature of the ruins provide a good glimpse into what this castle was like in its prime.  Even in relative ruins one can see examples of complex passages and hidden doorways.

Left, a view towards the great turret at the northwest side of the structure.

Below, left and right, two different views of the large, but relatively delicate, facade of the main quarters.  The walls are quite thin, and it is obvious that they were not designed to withstand any type of siege equipment, whether trebuchet or cannon.  As such, the inner part of the castle is more for ornamentation and appearance than for defensive functionality.  While the outer fortifications were fairly impressive, this egg-shell construction would bode ill for the castle when besieged.


Above and left, two comparative views of the Karl-Theodor Brucke across the Neckar as seen from the veranda of the castle.  Left, 1978; above, 2007.  Part of the bridge, such as footings, date back to the early 1600s.  The gate on the south side is featured in a city print from 1645, near the end of the Thirty Years War.

Some modest changes, including a clean up of the roofs, are obvious.
Above, two "then and now" photos.  Left, a photo of German Army soldiers taken prisoner in early 1945 by U.S. Army troops.  This was taken in the Marktplatz with the Herkules Fountain in the center.  Right, a photo of the Marktplatz from a different angle, with the fountain just visible in the right-center.  From this angle, the POWs were escorted along the left side of the photo.  The left photo comes from the USAREUR photo collection.
Two more "then and now" views of the Karl-Theodore Brucke.  The center span of the original bridge was blown by German Army engineers.  It was rebuilt in 1947.  Right, a view of the bridge in 2007.  The dark building to the left of the gate, seen on the right side of the left photo, is the same as the orange and dark yellow building to the left of the gate in the right photo.