Ula "ulpa" from Poland went on holidays to Malta. Malta is one of the countries i would like to visit, and look, postage there is cheap, only 0,37€ for a stamp to Europe :o I guess Ula send a few from there and i've received one of them with the Megalithic Temples of Ggantija, Mnajdra and Hagar Qim.
"The Megalithic Temples of Malta are a series of prehistoric monuments in the Maltese archipelago. Archaeologists believe that these megalithic complexes are the result of local innovations in a process of cultural evolution. This led to the building of several temples of the Ġgantija phase (3600-3000 BC) and culminated in the large tarxien temple complex, which remained in use until 2500 BC. After this date, the temple building culture disappeared.
The Ggantija temples were listed as a Unesco World Heritage Site in 1980. In 1992, the UNESCO Committee further extended the existing listing to include five other megalithic temple sites. These are hagar Qim, L-Imnajadra, Ta'Skorba and Tarxien. Heritage Malta today protects the sites, while ownership of the surrounding lands varies site-by-site. They are the oldest free-standing structures on Earth." - in: wikipedia