A mysterious package shows up in your mailbox. Inside, rhyming clues herald a great adventure yet to come. Indeed, this parcel—which also contains period artifacts and a guidebook with hints and historical info—is the key to an excursion through local history. Carefully designed by Double Key Treasure Hunts, the series of clues leads groups to a succession of historical or cultural landmarks, and at the end, the puzzle-busting scavengers uncover treasures ranging from a vial of gold flakes to an authentic antique silver coin.

Sure, you can zip from clue to clue, scurrying between the carousels, cathedrals, and museums at a breakneck pace. But it's not a race—every treasure will be securely waiting for you, so the real fun is in uncovering the hidden intricacies of your city, be it Boston, St. Louis, Deadwood, or one of six other cities that currently play host to Double Key adventures, as well as the memories you make together throughout the experience. Double Key can also personalize the experience with options such as adding a custom label to the gold vial.