Historically, Mixcoac included a greater area than it does today. The tiny neighborhood indicated is to the west in the map. Insurgentes Mixcoac is just to the east. The Church of Santo Domingo de Guzmán, founded by the Franciscans in 1595 is there.
The important archaeological site is today far to the north of the formal Mixcoac neighborhood. The remains we see today were from latest stages of Tepaneca occupation of the area. Under 15th century domination by the Mexica of Tenochtitlan, it became an area of annual celebration, hunting feasts, and music.
"Snake in the cloud," the meaning of the name in Nahuatl, still constitutes a motif that's common throughout many of these neighborhoods.
By the end of the 19th century, it was a wealthy and distant suburb. The 20th century may have been a bit less kind, but today you'll see that many of the corners and streets and places are just as well loved.