In this scenario, the PCs will be ordinary people who happen to be visiting the Met museum in Manhattan when things kick off.
What I intend to do is use the interactive Met map at https://maps.metmuseum.org to guide the players while they are inside the museum, or make it up on the fly if they venture into the 'employees only' areas of the Met not featured on the site.
Once they go outside, I intend to switch to Google Maps. Just open up the page, show them where they are, and ask what they intend to do next.
That is...intimidating.
What I need at the table is a method or mechanic to help me build content for each location they visit. Tools to help me narrate on the fly.
So, how would you prep an adventure like this? How would you manage it at the table? What tools would you have nearby to help you once you're in the trenches?