Then: In 2007 (the year it was disclosed that the 16-year project had racked up a $22 billion bill), a Massachusetts Turnpike Authority executive was accused of criminal negligence after a tunnel collapse killed a motorist.

Now: The Big Dig is finally complete and Boston has kicked off its latest effort to create a “better city.” David Straus, the director of A Better City’s sustainability and climate change initiative, heads the project, which launched the Challenge for Sustainability to encourage environmental awareness. As of June 2013, the program had reduced electricity consumption by 7%, which saved $5.7 million. It also lowered greenhouse gas emissions by 4%, or 7,000 tons, between 2011 and 2012.