These ruins were once an important building - it used to serve as a meeting chamber of the boulè (Senate), which also included a temple and a state archive. It was dedicated to the mother of the gods, Rhea. There is not much left to see now, but it's worth a stop on your way to Agora.
Daily: 8 a.m. - 3 p.m.
Last admission at 7:45 p.m.
Closed on Jan 1, Mar 25, May 1, Easter Sunday, Dec 25, Dec 26. Other holidays may have shorter opening hours.
Full: €8
Reduced: €4
Special ticket package:
Full ticket: €30
Reduced ticket (seniors 65+, students): €15
Free admission: Mar 6, Apr 18, May 18, the last weekend of Sep, every first Sunday from Nov 1 to Mar 31, Oct 28.
Wikipedia https://en.wikipedia.org/wiki/Metroon
Official website http://odysseus.culture.gr/h/2/eh251.jsp?obj_id=10302
Phone +30 210 3210185
Address Adrianou 24, Athens 10555, Greece
Coordinates 37°58'30.805" N 23°43'19.5" E