Itinerary followed during this Interrail throughout Germany, Denmark and Switzerland

Cologne - Koblenz - Copenhagen - Helsingor - Hillerod - Roskilde - Berlin - Potsdam - Rhine cruise - Freiburg - Strasbourg - Black Forest - Rhine Waterfalls - Schaffhausen - Stein am Rhein - Konstanz - Zurich - Basel - Interlaken - Luzern - Zermatt - Brig - Bern - Geneva - Heidelberg - Munich - Dachau - Fussen - Nuremberg - Rothenburg (ODT) - Wurzburg - Jungfrau and Lauterbrunnen - Brienz - Geneva

It is 45 min. far from Berlin if you take the urban train (U-Bahn). It could be described as the Berlin´s Versalles. Its main history starts during the 18th century.
Frederic William, called the Sergeant king, desired to convert Potsdam into a paradise. His son Frederic II considered Potsdam as his favourite residence. He built the Sans-Souci castle and the New palace. Potsdam was the residence for several emperors that continued creating new palaces, and that died here. In the so-called Garrison church we find the Frederic II´s tomb. Also here the Russian Zar Alexander I swore eternal friendship to Prussian king Frederic William III in 1805. Hitler proclaimed here the abolition of the Weimar´s constitution and announced the power of the III Reich (1933) in a spectacular ceremony. In 1945 Churchill, Stalin and Truman decided in Potsdam the destiny of the defeated Germany.
There are two zones, the village centre and the gardens with the palaces.
The village centre was once full of palaces, but nowadays there are little interesting things left. It´s nice the Dutch district the wooden houses and several buildings such as the city council or the house where Mozart lived in 1789. There are many antique shops.

The park possesses many treasures: palaces, streams and fountains, Chinese houses, a huge mill, statues. It is an immense park, so be ready for walking.
Go first to Sans-Souci castle , the sooner you arrive better. It is constituted by an single floor, and it is considered as the jewel of German rococo. It was Frederic II home and his friend Voltaire resided for 3 years. The outer part of the palace doesn't seem anything special, although gardens and fountains adorn it. Because we didn't arrive too early it was necessary to wait for hours to see the inside, so we didn't have that pleasure.

The greenhouse was the Frederic William IV refuge, also erected in Italian style. It is possible to visit Zar Nicolas I chambers.
You will be impressed by the New palace , at the end of the park. It is huge, with 400 rooms. From the inside we could highlight a room with a marine cave appearance, the marble gallery or a small theatre.
The Charlottenhof castle , near the roman baths, was also built in an Italian style, and it is worth visiting it.

You can go up to the mill or admire the Chinese house.
A little far from the village there you find the Marble palace or the Neogothic castle of Babelsberg , but we didn't see them.
So if you plan to visit Potsdam , calculate an entire day to avoid missing great things. The major problem is that the buildings are open from 10 to 17 h. during summer, so probably you will have to choose what to see.