Here's a little cheat sheet to help you navigate the map so you olds don't have to call your kids for help. It's okay. I'm an old too. These instructions are for using the map either within this webpage, or on your mobile device. The interface will be different if you are using the map within the Google Maps app on your mobile device.
A bit on navigation
You can click the little sliding door icon in the upper left of the map to open or close the list of items (see yellow circle):
If at any time you'd like to view the map larger and on Google Maps, merely click the window icon in the upper right of the map. It looks like this:
Pins
Pins are those little circles and inside the circle is an icon that is meant to give you an idea of what sort of item it is or what industry it came from. This is the color key for the pins:
You can slide around in the map and zoom in on specific sections by either using your mouse or fingers. Pinch zoom is helpful in getting close to the pin you'd like to see. Click or press on the pin to bring up a side-panel/window that will give you a brief history of the item as well as one to three historical photos of the item in its original iteration.
Photos
Use the arrow keys to swipe through the available photos. You can use your mouse or pinch zoom to embiggen images for a better look. To return to the map from the side-panel, merely press or click the left arrow (see left yellow circle). If you'd like Google Maps to give you directions to an item, click the forward arrow icon (see right yellow circle):
Known issue with mobile devices
There are some bugs! And as far as can be told, they are either Google Maps or Apple/Android issues. Your first jump to the map outside of this website to open the map in the Google Maps app will be successful. Occasionally, subsequent attempts in the same session to jump to the map in Google Maps app will not bring up the map or will bring up only the markers and photos, but not the history. A workaround is to use Google Maps without being logged into your account. You can toggle this in the app by pressing on your avatar/profile pic in the search bar, pressing the down arrow next to your user name, and selecting "Use Maps without an account." From this point, the map will open correctly every time.