Built in the second half of the 2nd Century, the Metroon, has four rooms that vary in size but share  a colonnade that faces eastward toward the square. Here is a picture of the overall plan of the Metroon.

This is the picture of the Metroon with Lykabettos in the distance.

The Metroon is located on the west side of the Agora and on the North side of Tholos.  Built over earlier Bouleuterion and earlier limestone foundations of Temple of the Mother of the Gods. The distinct units of the Metroon accommodated the Sanctuary of the Mother of the Gods, a council house and state record storage. Documents, such as, the proceedings of the Council of 500 and other official records  written on papyrus, parchment, and even on marble were kept in this building. The building also included a temple.

View of the Metroon from the West.

Remains that were left when the Metroon was built is shown here.                

This picture is of the center court of the large Northern room.

  The courtyard of the Metroon.

BIBLIOGRAPHY:

http://tantalos.perseus.tufts.edu/~hartzler/agora/site/guide/14.html

http://www.culture.gr/2/21/211/21101a/e211aa03.html

http://www.perseus.tufts.edu/cgi-bin/architindex?lookup=Athens,+Metroon

http://depthome.brooklyn.cuny.edu/classics/dunkle/athnlife/metroon.htm