Known casually as the "Cycladic," this institution has almost as large a collection of Cycladic art (3rd and 2nd millenia B.C.E.) as the National Archaeological Museum—and it's a much more pleasant place to visit. In addition to the Cycladic idols, whose elongated faces and body shapes remind many of works by Modigliani, there are stout stone and pottery vessels. The museum, just off Vasilissis Sofias Avenue, is connected by a passageway through the garden café to the elegant 19th-century Stathatos Mansion, which is used for special exhibitions. Even when there is no exhibit here, the house has some of its original furnishings and some additional period-appropriate pieces that give a sense of how wealthy Athenians lived one hundred-plus years ago. The museum shop offers a wide variety of books plus excellent reproductions of some of the Cycladic idols and vessels. You'll want to spend at least 3 hours on a visit, perhaps with a break in the garden cafe.