It hosted the high-elevation 1968 Summer Olympics.
A 1967 treaty named for a neighborhood in this city created the OPANAL to stop nuclear proliferation; a year later, that same neighborhood was the site of a massacre of the National Student Strike Committee. A fortress in this city was defended by the "Boy Heroes." This home to the Plaza of (*) Three Cultures, over 10,000 people died in a 1985 earthquake in this city. 400 years earlier, Pedro de Alvarado barely survived its noche triste. It hosted the high-elevation 1968 Summer Olympics. For 10 points, name this capital of the southern neighbor of the United States.
A 1967 treaty named for a neighborhood in this city created the OPANAL to stop nuclear proliferation; a year later, that same neighborhood was the site of a massacre of the National Student Strike Committee.
Mexico City [or Tenochtitlan or Ciudad de Mexico or Mexico D.F. or Federal District of Mexico or Distrito Federal de Meixco; accept Tlatelolco before "Boy Heroes"]