What is it about trains that fascinates so many? Is it their power? Their history? Their many moving parts? For whatever the reason, little kids especially are drawn to locomotives. And it is for them that the Children’s Museum of Sonoma County in Santa Rosa is holding the Great Train Days. The event, which will be held July 9–10, 10 a.m.–3 p.m., will feature the Redwood Empire Garden Railway Society’s display of model trains. Kids will get the chance to talk to train experts, build train tracks, dance to train-oriented music, listen to stories, and even ride on a miniature train. It’s free with admission ($14 or free for ages 0–11 months), though the train ride is an additional fee. For details, go to cmosc.org/train-days.