Austria’s most famous wine region isn’t very large, but what the Wachau Valley lacks in size it makes up for in scenic grandeur and the superlative quality of its products. Reminiscent in some ways of Germany’s Moselle Valley, the Wachau has steep, terraced vineyards tumbling down toward a large river, the Danube, which moderates the climate and reflects light, helping grapes to ripen. And like the Moselle Valley, the rugged and picturesque Wachau is dotted with little wine towns and the occasional castle.