Combine geo-referenced pdf map tiles into single pdf map in Acrobat Pro?

I don't know how to easily do this in Acrobat, but if you have InDesign, it could be done (in theory).

Here are the basic steps:

Create an InDesign document large enough to contain the combined maps.

Make sure smart guides are checked on.

Go to File> Place and place each map individually onto the page, the smart guides will indicate when they are correctly butted together (assuming they are all the same size).

When done, export to a new PDF.

If you need to preserve the PDF layers, there is a work-around that involves the use of InDesign object layer options. Create new layers in your InDesign document to match the PDF layers, then you will need to select an individual map, go to Object> Object Layer Options and turn off the visibility of all the layers except one, e.g. "Roads", in the layers panel, move this placed map to the corresponding InDesign layer, duplicate the map and move it to the next layer, using Object Layer Options to change the view again. Repeat.

Export to a new PDF, be sure to select "Include Acrobat Layers" when exporting the PDF from InDesign.

Vectors should be preserved, however, they won't connect from map to map. Spatial coordinates will probably also be lost.