Even if you have no idea what an HO scale line is, you'll still find the Walnut Creek Model Railroad Society mesmerizing. There is something hypnotic about watching miniature trains zip down itty-bitty tracks, past villages, through tunnels, across bridges, and by Lilliputian people forever stuck filling up at tiny gas stations. The museum houses nostalgic steam locomotives as well as modern diesels, all choo-chooing amid mountains delicately blanketed in fake moss along the more than 4,300 feet of hand-laid tracks. The Society, which started in 1948 after a group of hobbyists began meeting to share their passion, moved locations several times before finally landing a permanent home in Larkley Park in 1974. The dark-green, two-story building was the first in the state built solely for housing a model railroad. It is open on the last Friday and third Sunday of each month. If you visit, allow more time than you'd expect; it's easy to while away an afternoon here.