Hearts across the Bay Area melted as spectators watched a little boy’s dream come true – vanquishing enemies in a San Francisco transformed into Batman’s Gotham City.

Nearly 12,000 volunteers and adoring fans holding signs lined the streets Friday for Miles, who has been battling lymphoblastic leukemia since he was 20 months old and wanted to spend the day as Batman. 

More than 230,000 tweets with the hashtag #SFBatkid were sent out by the time Batkid’s adventures had finished, according to the Twitter analytics site Topsy. More than 19,000 Instagram photos were posted by Friday afternoon.

Bystanders and viewers following along with the help of social media and live-streams swelled with pride, many tweeting the event had “restored their faith in humanity.”

“So proud of the people of San Francisco, what a beautiful thing they've done for that little boy #SFBatKid,” Twitter user Sterling said.

Many wrote that they were misty-eyed and getting emotional watching from offices and homes across the nation.

“SOBBING! So many feels!! Miles, you are SO BRAVE!” Stefania Pomponi tweeted.

“All hopes of being productive today have gone out of the window as I follow the epic #SFbatkid events in Gotham City. Trying not to cry!,” Andy Weir wrote.

“Humans can actually be so great sometimes. #sfbatkid,” Kevin Douglas Grant sent out.

Coordinated by the Make-A-Wish Foundation, Miles' escapade was complete with donated Lamborghinis that were turned into Batmobiles, a personal call from Police Chief Greg Suhr asking for help and a live television broadcast kicking off the adventure.

Miles' cancer is in remission, and with the last of his chemotherapy in June, "he wanted to be Batman," Patricia Wilson, the Bay Area Make-A-Wish executive director, told the San Francisco Chronicle

Politicians and citizens alike joined the fun. President Obama, posting a Vine, thanked the boy for saving the city.

House Minority Leader Nancy Pelosi of San Francisco and East Bay Rep. Eric Swalwell also called on Miles to save the day and commended his bravery. Standing on the steps of the Capitol in Washington, Swalwell recorded a personal video message to Batkid, saying he would be flying home to a hopefully safe Bay Area that evening.

“Batkid, Gotham city in California needs help,” he said. “We’re all counting on you, Batkid, to use your superhero powers to protect our city.”

Even the U.S. attorney's office and FBI got in on the citywide spectacle that had captured the nation's hearts and minds, particularly on social media.

Melinda Haag, U.S. attorney for the Northern District of California, and FBI Special Agent in Charge David J. Johnson issued a statement Friday announcing formal charges against the Riddler and Penguin, indicting them on multiple counts of conspiracy and kidnapping for their "all too familiar villainous ways in Gotham City."

The Twitter handle @sfbatkid had gained more than 16,000 followers just after 3 p.m. 

As the small superhero peered out onto Union Square from the top of the Macy’s building, thousands of people jumped and cheered for Miles, some holding a giant sign that read “Help us Batkid” and motioning for him to save the kidnapped Lou Seal.

“I can’t even imagine what that was like for him,” said Jessica Harris, 35, who took the day off work with her husband to dress in yellow and black and relive a little bit of childhood.