I have long been a fan of Google Arts & Culture (previously Google Art Project). It allows individuals to explore museums, exhibits, and historical topics around the world. For example, you can tour the works of Vincent Vangogh, explore Ancient Kyoto, or wander around the Lincoln Home (to name a few).
Previously, the robust features of Google Arts & Culture was reserved for computers. Now, however, you can download the free pap for your iOS or Android device. This is a great way to let students explore the different tools and features available via Google Arts & Culture on your classroom tablets or even on student smartphones!