<p>Postcard -  Piccadilly, with entrance to Leipziger Platz U-Bahn]  pre-Haus Vaterland  and Potsdamer Platz UBf days as Piccadilly Haus with the Cafe Piccadilly.   Potsdamer Platz  [Koeniggraetzerstr 130 and Koethenerstr 1-5]    In ruins 
1951
&lt;a href="<a class="external free" href="https://upload.wikimedia.org/wikipedia/commons/7/7c/Fotothek_df_roe-neg_0006160_004_Begegnungen_von_Weltfestpielteilnehmern_am_Potsd.jpg">https://upload.wikimedia.org/wikipedia/commons/7/7c/Fotothek_df_roe-neg_0006160_004_Begegnungen_von_Weltfestpielteilnehmern_am_Potsd.jpg</a>" rel="noreferrer nofollow"&gt;upload.wikimedia.org/wikipedia/commons/7/7c/Fotothek_df_r...&lt;/a&gt;  
</p><p>The underground station was opened on 28 September 1907 only becoming Potsdamer Platz in 1923.
</p><p>Posted December 15 1912 to Zittau from Postamt W9. postmarked 4-5 AM,  but written, no doubt late in the evening in the restaurant where the sender is sitting with his relatives.
</p><p>The Haus Piccadilly was built 1911-2
&lt;a href="<a class="external free" href="https://en.wikipedia.org/wiki/Haus_Vaterland">https://en.wikipedia.org/wiki/Haus_Vaterland</a>" rel="noreferrer nofollow"&gt;en.wikipedia.org/wiki/Haus_Vaterland&lt;/a&gt;
By the end of 1914 it had been renamed, thus dating this postcard to 1912-4
it certainly appears in the 1915 Berliner Addressebuch as Haus Vaterland with the  Neue Kammer Lichtspiele. Address Koeniggraetzerstr 15/16.
The other side of the Potsdamerplatz, in the same street  
no 10 - Hotel Saronia
no 11   Hotel du Parc aka Tiergarten Hotel
</p>
no 12 Grand Hotel Bellevue
<a rel="nofollow" class="external text" href="https://www.flickr.com/people/28179929@N08">Sludge G</a>
CC BY-SA 2.0
<a rel="nofollow" class="external text" href="https://www.flickr.com/photos/sludgeulper/49970588358/">Postcard -  pre-Haus Vaterland: Piccadilly Haus</a>