Why Mexico city was chosen as an ancient capital.?

Answer 1

Before 1325 AD, the Aztec or Mexica people were a nomadic tribe that wandered throughout the land, looking for a place to settle and build their capital. Their state religion awaited the fulfillment of an ancient prophecy: that the wandering tribes would find the destined site for a great city whose location would be signaled by an eagle eating a snake while perched atop a cactus.

The Aztecs saw this vision on what was then a small swampy island in the middle of lake Texcoco, after which they founded their capital Tenochtitlan (today known as Mexico City), on March 13, 1325.

The prophesy and subsequent vision is now immortalized in Mexico's coat of arms and on the Mexican flag.
Before 1325 AD, the Aztec (or Mexica people, as they called themselves) were a nomadic tribe who wandered throughout the land, looking for a place to settle and build their capital. Their state religion awaited the fulfillment of an ancient prophecy: that the wandering tribe would find the destined site for a great city whose location would be signaled by an eagle eating a snake while perched atop a cactus.

The Aztecs saw this vision on what was then a small swampy island in the middle of lake Texcoco, after which they founded their capital city, on March 13, 1325. Not deterred by the unfavourable terrain, they set about building their city, using the chinampa system (misnamed as "floating gardens") for agriculture and to dry and expand the island. That city was Mexico-Tenochtitlan, now Mexico City (19° 25' 57.85'' N, 99° 07' 59.71'' W).

The Mexican Coat of Arms, which also appears on the Mexican national flag, illustrates the fulfillment of this prophesy.
It had a volcano