Yellow is the colour of the sun that strokes the picturesque Mediterranean towns on the Adriatic coast. Its rays are infatuated with the beauty of the karst region planted with olive groves and vineyards, with peach orchards and cherry trees. Some of the most beautiful underground worlds of our planet lie below their roots. There are more than six thousand karst caves and sinkholes in Slovenia, and ten of these treasuries of limestone masterpieces created by disappearing karst rivers have been adapted and opened for tourists. Every kilometer of the Slovene coast is a new surprise. Here is a natural reserve with a rich fund of marl and sandstone and the unique, eighty-meter Strunjan cliff, the highest flysch wall on the Adriatic coast. Here are the Secovlje saltworks, first mentioned in the 13th century, and nearby is a sanctuary for more than 150 bird species. Here the towns of Piran, Izola, and Koper draw visitors with their medieval cores, while Portoroz, though mentioned as early as 1251, offers numerous modern hotels with congress halls, a fully equipped marina, a sport airport, thermal baths, a casino, and a varied offer of summer cultural, entertainment, and sports events. Not far from the coast, the beauties of Slovene Istria with its picturesque villages await you. Among them, for example, is Hrastovlje with its Holy Trinity church decorated with narrative late Gothic frescoes including a marvelously preserved Danse Macabre. Behind the Slovene coast is the karst region. In the cellars of the stone houses excellent wines are poured and sold, and in the attics excellent prsut is cured in the bora wind. This gourmets' paradise is also a heaven for lovers of the beauties of the karst underworld. Postojna Cave, first mentioned in 1213, is the most popular cave in Europe with more than twenty-six million visitors so far. The Skocjan Caves, which are on UNESCO's list of natural and cultural world heritage sites, boast the 1400-meter long and 150-meter deep underground canyon of the Reka River. The beauties of the Krizna jama Cave lakes can be seen from boats in the glow of carbide lamps. In Slovenia, whose language contributed numerous terms to world karst studies, we also find the oldest tourist cave in the world: Vilenica near Divaca which offered guided tours in the first half of the 17th century. The only cave vertebrate in Europe, the Proteus anguinus or "human fish" which is also the largest known cave animal in the world, lives in Slovene caves. And this is far from being the last of the attractions of Slovenia's karst region. Perhaps you didn't know that the noble Lipizzaner horse originated in Slovenia. Lipica, where the stud farm was established in 1580, is today a popular tourist center with a riding school, hotels, a swimming pool, a golf course, and a casino.