This undeniably grand home of pale carved limestone in the Beaux Arts style, designed by turn-of-the-20th-century architects Clinton & Russell, is in its element on what’s known as the most valuable corridor on the Upper East Side just across from Central Park. And unlike many of its kind, the interiors of the 25-foot-wide, 11,500-square-foot mansion at 7 East 67th Street are neither overly opulent and intimidating nor tastelessly renovated. There’s an elevator, gym, double-height library, two grand staircases, and decks and terraces around every turn. Why, then, has this home been seeking a buyer since 2009? It’s certainly possible that when other houses like this are asking less than half its current price of $36.5 million, an ask of $37 million nearly a decade ago that hopped to $49.5, fell to $42.5, and steadily dropped since then might have less appeal for buyers when the choices are many.