Museums of the World is a website and mobile app that gives you information about museums all over the world, and the Exhibitions, Collections, and Events associated with them.
You can visit museums virtually before you visit in person. The mobile apps let you find museums using GPS, and then guide you through the museums as you visit. Or you can use the site/apps to help you read about or research a work of art that interests you. There are plenty of images and also some videos, not all of which are in English, but if you’re studying another language besides English, this is a good place to get some more listening/reading practice.
The free app is available for both iOS and Android.
Screenshots of the iPhone app: