Google has released the Google Expeditions app for all. Users just need Google Cardboard and an Android or iOS phone. The app, mainly intended for educating students, allow users to explore a 360 view of photos and scenes from certain historical periods. There currently over 300 types of expeditions available (google docs warning) with tours visiting various locations and areas of the subject. Download can be found at this link.
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Source: [H]ardOCP – Google Opens Expeditions VR Education App to the Public