Hi there! I understand you’re looking for the "Book" button for the Natural History Museum in the Go City app, but it's not showing up. Let me help you sort that out.

First, just to clarify, do you already have a Go City pass purchased and logged into the app with the same email you used to buy the pass? Sometimes the book button appears only if the pass is active and recognized within the app.

Assuming you’re logged in with your pass, here’s a step-by-step to troubleshoot:

1. Check if Reservations Are Required:
Within the Go City app, attractions that need booking usually have a “reservations required” note or a stamp. For the Natural History Museum, Go City typically requires booking a time slot in advance. If this note isn’t visible, it might be hidden behind some other menu or possibly the booking window isn’t open yet.

2. Look Under ‘Reservations’ or ‘My Pass’ Section:
Instead of directly on the museum page, sometimes the app requires you to go to a Reservations section where you can enter your pass/order number and the email to find and book available time slots.

3. Update or Restart the App:
Bugs can cause buttons to disappear. Fully close the app and reopen it. If an update is pending on the App Store, installing that might resolve interface issues.

4. Try Booking via the Website:
If the button still doesn’t show, you can make a reservation for your Natural History Museum visit by going to the official Go City reservation page at https://gocity.com/en/new-york/reservations, where you enter your order number and email to book your slot. Then you can use the app to access your pass on-site.

If after trying these steps the book button is still missing, just let me know. We can look deeper into app settings or your account details. Does that make sense so far? Would you like me to walk through any of these steps with you?