Sail through a serene tapestry of terraced vineyards, forested slopes, charming towns and castle ruins in Austria's Wachau Valley, celebrated as perhaps the most scenic stretch of the Danube. Journey 18 miles through this vast UNESCO World Heritage Site, where the river courses through picturesque hillsides. Gaze upon the prolific grapevines and quaint wine-producing villages hugging the shores—the legacy of vintners that stretch as far back as Celtic and Roman times and an echo of the more than 30 monasteries that served as vineyards in Renaissance days. A small university town at the eastern end of the Danube's Wachau Valley, Krems is surrounded by terraced vineyards. In its heyday, during the 12th century, Krems held even more importance than Vienna for its iron, grain, salt and wine trade. As to the latter, the city has played a long and celebrated part in the popularity of the Wachau's wine culture; the valley's south slopes in Krems are bathed in sunlight all day and create some of the best Riesling and Veltliner wines in the world. The city's cobblestone streets, taverns, wine bars and cafés have a timeless appeal.