The Last Chance Mine sits high above Creede, Colorado, in the heart of the San Juan Mountains, and it's a remarkable thing: a real silver mine, open to the public, with 13 levels and some 30 miles of tunnels running back into the mountain. Better still, admission is free. In a state where mine tours routinely cost real money, the Last Chance offers a genuine underground experience, a museum and a gift shop for nothing more than showing up.

The underground tour is the reason to come. It runs about 30 minutes and departs from the mine's gift shop, with the first tour at 10:30 a.m. and the last beginning at 4:30 p.m.; reservations aren't necessary, so you can simply arrive and join one. The mine's signature is geological: this is the only mine in Creede where you can see the Amethyst Vein, containing amethyst, sowbelly agate and silver, which is exactly the kind of specific, real thing that separates a good mine tour from a gimmick.

Practicalities are worth knowing up front. It's 50 degrees in the tunnels year-round regardless of the weather outside, and closed-toe footwear is required, both sensible rules for an active mine. The operation is cash only, so plan accordingly, and it's closed on Wednesdays. The season opens each year on Memorial Day weekend, with hours generally 8 a.m. to 5 p.m. and the museum and gift shop running 10 a.m. to 5 p.m.

Rock hounds get a bonus. There's a public collecting area where you can gather specimens for about two dollars a pound, which for anyone who has ever wanted to dig their own amethyst out of a Colorado mountain is a genuinely fun proposition and a good way to send kids home happy.

The setting alone justifies the drive. Creede is a former silver boomtown tucked into a canyon in the San Juans, one of the most scenic corners of Colorado, and the road up to the mine climbs into high country with big views. At this elevation the season is short and the weather changes fast, so layers are wise even in July.

Come with a jacket for the 50-degree tunnels, closed-toe shoes, cash, and a bag if you plan to collect. Between 30 miles of tunnel, a visible amethyst vein, a mining museum, free admission and a scenic Colorado boomtown at the bottom of the hill, the Last Chance is one of the best free attractions in the San Juans.