DOORSOPEN (9/20/14) Mason Prentice posed so his mother couold take a picture as he sat in the drivers seat of Milwaukee Fire Departments Engine One Saturday. Doors Open Milwaukee runs Saturday and Sunday from 10 a.m. to 5 p.m., with more than 150 buildings letting you in to check out hidden treasures and learn more about the city and its history. Historic Milwaukee Inc. organizes the annual visual scavenger hunt, with ticketed tours available.PHOTO FOR THE JOURNAL SENTINEL BY JOHN KLEIN