ROBERT PATTINSON was photographed with a "mystery blonde" at the Dream Hotel in New York City over the weekend.  (--Yes, that's the same place Lindsay Lohan and her mom were partying before their big fight yesterday morning.)

--And there are pictures to prove it.  (--Here they are.)  (TMZ)

--They weren't alone, so it wasn't necessarily a date.  But a source says, quote, "It looked like Robert only had eyes for the girl . . . they sat really close to each other on the couch."