Knowing some folk who BT like to use Herospace tiles for same, had a bit of an idea I'd thought I'd share, just to see how if 'floats'.
u-build Monopoly was a failed bit of Hasbro marketing to make a you roll your own board.. Clip together tiles can be strung in various paths. However, they included several new features, including drawbridges, high rises, stadium, nuclear plant, etc.
As you may be able to see, the tiles fit over the Heroscape ones, but fill the space in between, so you cannot place them side-by-side. For the heck, I put some of the 'houses' and 'hotels' to fill space between.
This is the underside of the GO tile. It has three connector tabs; most of the buildings have one. Tabs must be removed to get them to set down at all. However, someone might want to take a razor saw to the sides, just leaving the 'indents', and might be able to set them snugly together.
I tend to find cast off u-build games at thrift stores, often for $2USD, but even brand new from Amazon at less than $5USD may tempt some.
Do flame about anything other than 'scale'; silly, I know.
Doug