Long histories produce compelling mysteries and, with a little cryptic religious element involved, adventurous memories with your friends. That’s a colorful way of saying that you should visit Temple Church–a fascinating, round, 12th century church built by the Knights Templar–on your next outing with friends in London. Looming in an otherwise gray courtyard, the beige rotunda is eerily mismatched with the surrounding buildings. Pause with your group and ponder the knight atop a pedestal in the courtyard, sleuthing out any hidden meaning in the coat of arms on his shield. After navigating to the iron gate in the back, ease open the filigree-covered wooden door as your friends cautiously step inside. The décor may be simple, but there’s more than meets the eye in this austere hall, where the early crusaders plotted their conquests and established an economic system for the church. Look upwards to the stone faces of long-dead Templars, then catch up with your friends in the center, where supine effigies of some of the first knights are posed as if ready to spring into battle. Each effigy was painstakingly created by skilled artisans, so look closely for suprising details, and don’t jump out of your skin when you notice a speared head at the base of a knight’s sword, as the art reflects the violence of the times. As an organist settles onto a creaking bench and runs through a minor key dirge, guide your friends out and ponder what other mysteries might lie right beneath you in this ancient, yet modern, city.