I built ExploreHere | Markers App (iOS), two years ago to help fill some of the void that FieldTrip left. It has over 200k historical and interpretive markers so you can learn a bit about whats around you.

Based on feedback from the community, I'm currently working on an Audio-Guide version that generates and reads interesting stories aloud to you as you drive, all hands free! If you're interested, I'd love to send you the beta and see what you think!? https://testflight.apple.com/join/ExaAqkU8