A condo sale anywhere near the $5 million mark in Brooklyn is always notable, but it’s especially so in the case of the recent penthouse purchase at On Prospect Park, since it’s far and away the most expensive unit to sell in the building so far. The purchase, which was recorded in public records yesterday, is for “PH16N” in the Richard Meier-designed building, and the buyer is not at all identifiable via public records, having an LLC name of “3GAP.” The completely unsubstantiated gossip we have heard is that the buyer already has another unit in the building. StreetEasy’s listing for the unit says it is 3,274 square feet and has four bedrooms. And, hey, the common charges are only going to be setting the buyer back a mere $3,692. At $4,900,000, this is one of the biggest condo sales ever recorded in Brooklyn, and the next most expensive listing at OPP is for a $3.25 million penthouse. Click through for the floor plan. Update, 5/2/12, 12:06 p.m.: Well, forget about “PH16N”: A deed recorded in public records today shows that “PH16S” sold for $5,100,000. No word on this buyer, either!