I discarded the square designs because the shape of the gray stone makes it hard to tell which shape is being defined and the center area looks like a pillar. I really like 18 but it needs a little more 'pop' to define it. maybe stonehenge in white font or construction of buffalo in white font. Thank you again for your entries.
I didn't see that negative space in the discarded :D but yeah, it's kind of hard to distinguis. I focused on #18 an updated to the directions you provided.
Hope you like it. Anyhow don't hesitate for changes. :D