Heidelberg
Heidelberg is a university city, and was once the seat of the Elector Palatinate.  During the early 1600s, this seat was held by the Elector Frederick, who was related by marriage to the King of England.  At that same time, the Holy Roman Emperor was Mathias, of the House of Hapsburg, who had been elected in 1612 in a split decision of the seven electors.  At that time, the three eclesiatical electors were Catholic (Koln, Mainz, and Trier), along with the King of Bohemia.  Three electors (Brandenburg, Saxony, and Palatine) were Protestant.  In March of 1619, Mathias, who was childless, died.  By the summer many of the Protestant princes were declaring that Ferdinand of Styria was not to be their king, and it was then that the Bohemians chose their king... Frederick Elector of Palatine.  By doing this they gave Frederick TWO electoral votes for the position of the Holy Roman Emperor, and thus gave the Protestants a 4 to 3 edge.  The Catholic party realized this could not be, and went to war.  Thus started the Thirty Years War, which would soon engulf the city and castle of Heidelberg.

The castle was started about 1400 by the Elector of the Palatinate Ruprecht and over the next 200 years was gradually expanded from a basic fort to a huge castle complex.  In 1622, the army of the Catholic League under Count Tilly besieged and captured the city and destroyed the castle.  Later efforts to rebuild the castle were stymied, first by the French in 1689, and later when a lightning strike in 1764 ignited the structure and led to massive damage.  In the late 1700s, the people of Heidelberg began to help themselves to the castle's stones to build their own houses, a practice ended by Count Charles de Graimberg about 1800.  The King's Hall was not added until the 1930s and is today used for a number of festivities.
Top, Heidelberg castle panorama from 1978, a combination of two separate photos taken with my 35mm camera.  A view of the castle taken in September 2007.  Unfortunately the scaffolding spoils the view, but the results of the "face lift" it is receiving is obvious.  Below, an idyllic view of the castle from the park on the opposite side of the river.  Here, university students and locals come to relax.  Taken in 1978.
Above, the sheer size of the Heidelberg castle is amazing.  Not only is the castle itself quite large, but the grounds surrounding it are extensive.  Today these are well-kept, and the castle is a favorite for weddings and photo opportunities.  This photo taken in 2007.

Left, the northeast tower of the castle as seen in 1978.  In 2007, the tower was encased in scaffolding and thus a "then and now" comparison was meaningless.  The small cylinder along the side is where a staircase would have been, while the tower itself had multiple stories with wooden floors resting on cross beams that in turn were suspended on stone footings.

Below, one of the towers along the outer wall, clearly showing the stone footings for the wooden floors.  The floors would be constructed of planed boards with a series of large joists to secure the floor as a single unit.  Along each edge would be a joist that would rest on the footings.  Of course, if the castle caught fire, these floors would make excellent fuel for the flames!
Below, an excellent "then and now" comparison of one of the main turrets along the back, or hill-oriented, side of the castle.  This tower was blown up by the French in the 1689 during the War of the Palatinate Succession.  The explosion in this tower was so massive that it blew 1/3 of the structure outward, revealing the inner design of the turret.  The design was mostly Romanesque, evident by the heavy arches to support the roofs of the structure.  However, the castle also contains elements of Gothic, and even a hint of Baroque, that was instituted during efforts to rebuild it.