Final answer:
The provided materials do not contain information about the specific event that took place in the basement of the Municipal Auditorium in 1966; hence, no accurate answer can be given. Research in credible history sources or local archives is recommended.
Step-by-step explanation:
The question is about a significant event that took place in the basement of the Municipal Auditorium in 1966. Unfortunately, the materials provided do not contain information about this specific event. As there is no relevant information to conclusively determine the event in question, it is advisable to research using credible history sources or local archives that could have recorded events at the Municipal Auditorium during that time. It's important to note that the given information covers different historical events such as the assassination of Harvey Milk and George Moscone in 1978, the construction of a new ballpark in El Paso in 2012, and significant occurrences in 1968. If the event at the Municipal Auditorium is related to any of these subjects or dates, further details would be needed to provide a precise answer.