Saint Stanislaus chapel in the Polish village of Chwarszczany, built by the Knights Templars.
Who doesn't enjoy a little bit of Knights Templar gossip? Smithsonian Magazine reports that crypts and a possible "secret tunnel" have been found beneath a Polish church built by the Knights Templars.
A Knights Templars member is a major character in Robert Shea's novel, All Things Are Lights, they are mentioned in Illuminatus! and as the Smithsonian piece mentions they of course are featured in many other works, including Dan Brown's The Da Vinci Code.
Hat tip, Jesse Walker on Twitter.