These beautiful series of 12 stamps  with architectural landmarks of occumpied Poland was issued by Germans for the use in General Government in 1940.
 
You can receive the following configurations of these stamps:
a strip of 5 identical stamps presenting one of the landmarks 
a block of all 12 stamps (one of each, full series) 
 
Stamps in the series (sorted by price):
6gr - Florian's Gate, Krakau
8gr - Sandomiersk Bastion, Castle of Krakau
10gr - Krakau Gate, Lublin
12gr - Old University, Krakau
20gr - Dominican Church, Krakau
24gr - Wawel, Krakau
30gr - Brigitta Church, Lublin
40gr - Sukiennice Arcade, Krakau
50gr - Tower of the City Hall, Krakau
60gr - Castle, Krakau
80gr - St Mary's Church, Krakau
1zl - Brühl's Palace, Warsaw