The (usually rose-colored) glasses which one views the past. Viewing through retrospectacles causes one to overlook past problems or disasters and remember only the good aspects. Thus, retrospectacles are often the device which allows one to intentionally repeat the same ill-advised course of action.
Adam: "I know she cheated on me the last 5 times we got together, but we had some really good times too. Maybe this time will be different, I think I'll give her a call"
Bob: "Adam you idiot, put down the phone and take off your retrospectacles"
A Shackteau is a humble, weather-beaten, structurally questionable shelter located in a spectacular or highly coveted place—Wales, Jackson Hole, Sun Valley, Crested Butte, coastal Maine, the Alps—where the building itself may be worth almost nothing, but the dirt, view, access, and mythology make it absurdly valuable.
In use:
Shackteâu - We thought it was an abandoned shed until the realtor called it a rare alpine Shackteâu with unobstructed views and listed it for $2 million.