Thank you Alberto! Posted from the Vienna office of the UN, the lower stamp comes from a set of 6, and shows the c. 1250 BCE Lion Gate from Mycenae. Constructed using cyclopean masonry, the gate is the last surviving monumental example of Mycenaean architecture. Whether or not the lion gate should in fact be called the lion gate is debated. The heads to the lion bodies are not present, and, due to the fact they were carved from separate blocks than the bodies; some have suggested that they may represent a mythological creature, such as a sphinx. 
Postcard with the gate.