A controversial bus displaying a transphobic message landed in Boston this week, prompting protests and a powerful demonstration of solidarity from Mayor Marty Walsh.

The "Free Speech Bus," which raised eyebrows when it rolled through New York City last week, arrived at Boston City Hall early Thursday morning before making its way to the State House and later to Cambridge.

The bright orange vehicle sports graphics of a boy and girl along with the message: “It’s biology: Boys are boys... and always will be. Girls are girls... and always will be. You can’t change sex.”

The bus is sponsored by several conservative groups, including the National Organization for Marriage, CitizenGo and the International Organization for the Family.

Joseph Grabowski, spokesman for NOM, said Thursday’s visit was all about raising awareness for issues surrounding “so-called transgender rights,” and differing viewpoints on anti-trans bathroom bill legislation.

“Unfortunately, [the issue] seems to be on a collision course with other rights of other citizens,” Grabowski told the Boston Globe, specifically citing religious freedom and the right to free speech. “We are trying to have a respectful policy discussion that considers everybody’s concerns.”

Not long after pulling into the capital city, the bus was met by protesters, who vandalized the vehicle and spoke out against its discriminatory message.

After it made a stop at City Hall, Mayor Walsh delivered a speech condemning the bus and vowed to continue standing in solidarity with Boston's transgender community.

“We will not be intimidated by discrimination or harassment," Walsh said to the crowd of college students, elected officials and protesters gathered outside City Hall. “And we will not tolerate these types of actions. When you deny the experience of transgender individuals, you are denying the experience of basic human civil rights.”

He concluded: "[My office] is always going to support our transgender community and defend their fundamental rights."

Boston stands with transgender community. pic.twitter.com/kTXYWcRlzr

— Abbi Matheson (@AbbiMatheson) March 30, 2017

Following his speech, the mayor raised the transgender pride flag on the plaza alongside Alex Zafris, a transgender woman who serves as his deputy director of scheduling.

"Now go back to work." @marty_walsh pic.twitter.com/DAAIaJPWCp

— Abbi Matheson (@AbbiMatheson) March 30, 2017

Freedom Massachusetts, an organization that fights for the equal treatment of transgender people statewide, called the bus "downright frightening."

"This bus is the embodiment of the kind of harassment and discrimination that study after study documents our community combats on a daily basis," said group co-chairs Kasey Suffredini and Mason Dunn.

"We are thankful to Boston Mayor Walsh for raising the transgender flag today on City Hall Plaza to remind us that Boston is a fair and welcoming city and to all the first responders who are keeping all of us safe during this toxic invasion of our city and state."