“Henry’s Hideaway” is the provocative title of my latest Unreal Estate column for Avenue, on the famously secretive River House cooperative on 52nd Street at the East River. Yes, it’s the home of stuffed shirts like Henry Kissinger, but some of what you know about it is wrong, and as the column reveals, a lot has just changed there. Among other things, it may now be the best bargain in New York for trophy apartment-seekers. UPDATE: Max Gross at the New York Post picked up my River House reveal yesterday.