Supporters of Gustavo Petro attend the Plaza de Bolivar to see his inauguration as president of Colombia in the center of Bogota on Sunday. Photo by Mauricio Duenas Castaneda/EPA-EFE

The inauguration ceremony was held in Plaza de Bolivar, a large square in front of Colombia’s Congress, with live music and large screens to view the events.

The former rebel joined the M-19 guerrilla organization when he was a teenager and helped form a political party called the M-19 Democratic Alliance when the group was demobilized.

He holds a master’s degree in economics and studied toward a doctoral degree in public administration and first joined the country’s legislature as a representative in 1991.

Petro was appointed to the Colombian Embassy in Belgium as a diplomatic attaché for Human Rights from 1994 to 1996 and returned to Colombia in 1998 where he again was elected to the House of Representatives representing Bogotá after campaigning against corruption in the country.

He served as a senator from 2006 to 2010 and was elected mayor of Bogotá in 2012 and served in that role until 2015 before returning to the senate in 2018.

“Tomorrow I’ll wait for you in the center of Bogotá. May Aug. 7 be a great popular festival,” Petro said in a post to Twitter on Saturday.

Márquez, his running mate, is a 40-year-old lawyer and human rights and environmental activist and, along with becoming the first Black Colombian to be elected vice president, is only the second woman to hold the office.

“Thank you, Columbia. This fight did not begin with us, it began with our ancestors,” Márquez said on Twitter after winning the election. “Today with dignity and greatness we reap the fruits of that sowing.”