Recently approved to start building a $175 million waterfront museum on Piers 15 and 17, the Exploratorium (the city's finest hands-on museum) just received a whopping $90 million donation care of two anonymous donors. "The Exploratorium has outgrown its current home at the Palace of Fine Arts," reports SF Business Times. "The planned new museum would be three times larger." Now all they need is an additional $40 million, and they're in business.