As the City of Colorado Springs enters its 150th year, the City is getting ready to celebrate the milestone with an array of activities available all year.  On Monday's "Extra" show, the city's cultural services manager and director of the Pioneers' Museum Matt Mayberry joined host Shannon Brinias to discuss the city's history:  On July 31, 1871 a group of citizens along with General William Jackson Palmer gathered at the southeast corner of Pikes Peak and Cascade avenues and declared Colorado Springs as an established city within the state of Colorado. They sealed their declaration by driving an iron stake into the ground. On July 31, 2021, Colorado Springs, now the 39th largest city in the United States, will officially turn 150, and its citizens will once again gather to celebrate.  More information on how to participate in activities and learn more about how the city's events will mark the sesquicentennial can be found at ColoradoSprings.gov/150   and  cspm.org/cos150.   Mayor John Suthers has also issued a challenge to the city's residents to take part in the Tree Challenge, to add 1,871 new trees to our canopy of green.