We were prompted to conduct research on a building/monument that

was constructed between Ancient times and the Renaissance era. I

chose to write about the Co Loa Citadel because not many Vietnamese

architectures are well-known, and I see that as a challenge. Based 

on the information I found, it was considered the oldest citadel in

Vietnam. It has a legend about a king who constructed the citadel to

protect himself from invaders by using a magic crossbow from the

golden turtle.