Leading Edge of a Developing Territory, Settlement
This page is the CodyCross answer for the clue below from Trip to Spain, Group 856, Puzzle 5 (Historic Landmarks).
Question is: Leading Edge of a Developing Territory, Settlement
and the answer is: FRONTIER
Word Meaning:
FRONTIER — The part of a country which borders or faces another country or unsettled region.
Definitions from Wiktionary.