Michael and Susan Dell Put Their Boston Penthouse on the Auction Block

The Dells have two luxury penthouses in Boston. They have been quietly trying to offload both.

The first, a $34 million duplex atop the Four Seasons Private Residences at One Dalton Street, was listed in 2023, reduced to $29 million, then pulled from the market entirely. The second is now going to auction.

That second unit: a 59th-floor penthouse at Millennium Tower, bought in 2016 for $10.9 million, barely used, and now hitting the block with a $6.5 million reserve. Paramount Realty USA and SERHANT are running the sealed-bid sale, closing October 29…