15 letters Mental eccentricity ... as suggested visually by some of this grid's black squares Answer: BATSINTHEBELFRY
15 letters Thing that may appear to be symmetrical but isn't ... like this puzzle's grid Answer: OPTICALILLUSION
15 letters Q: "Should you call that stopover between Liverpool and Belfast a peninsula?" A: "___" Answer: NOMANISANISLAND
15 letters What you might do after some financial trading ... or in this puzzle? Answer: CORNERTHEMARKET