Dwarfed by the looming Sierra Ponce, the cluster of buildings that make up the Castolon Compound were built in 1920. A half-mile historic stroll offers a brief look at life on the frontier in the Castolon Historic District. Start at the famous La Harmonia Store, which is a mainstay for locals on both sides of the river as well as an ice-cream vending oasis for tourists. A pamphlet ($1) sold in the store serves as a guide.