Complex sentence: At the same time, the vehicle sitting idle in Palo Alto, California sat untouched for more than a week until Zimbardo himself went up to the vehicle and deliberately smashed it with a sledgehammer.
Split into simpler sentences: At the same time, the vehicle sitting idle in Palo Alto, California sat untouched for more than a week. Then Zimbardo himself went up to the vehicle and deliberately smashed it with a sledgehammer.