-  A viewer with a view  (© Jan Greune/Alamy)

The Sphinx Observatory isn’t the highest astronomical observatory on Earth, but it might feel like it to the lucky travelers who visit. To reach the observatory, they take a train up into the Alps, alight at Europe’s highest railway station, and ascend in an elevator tunneled inside the mountain. Once on top, stargazing is the academic focus, but visitors can take in sweeping views from the Sphinx’s 11,716-foot vantage. On either side are the Jungfrau and the Mönch, both members of the ‘four-thousander’ club—mountains that tower at least 4,000 meters (that’s 13,123 feet) above sea level.