There’s no official guided tour, but plenty of local guides offer tours of the Hagia Sophia. If you do your research then it’s well worth taking a tour as an expert guide can add a great deal to the visit, fleshing out what might be lacking from signs and helping to paint a picture of the importance of the Hagia Sophia to the history of Istanbul. An audio guide is also available in 12 languages including Turkish, English, French, German, Italian, Spanish, Arabic, Japanese, Persian, Greek, Russian, and Korean, if you don’t want to hire a guide but would like some more context for what you’re seeing.