When a spot is holy in Greece, it has usually been holy for a very long time. Today's monastery occupies the site of an ancient temple to Aphrodite, probably built here because of the spring, part of the headwaters of the River Ilissos that flowed through Athens in antiquity. You'll see the water pouring through the open mouth of the marble goat's head at the monastery's entrance. This spring once supplied much of Athens with drinking water. Now, Greek brides who wish to become pregnant often journey here to drink from the spring, whose waters are believed to speed conception. The monastery was built in the 11th century over the ruins of a 5th-century Christian church, itself built over the temple. The monks supported themselves by keeping bees and selling the honey. The monastery's kitchen and refectory, which now house sculptural fragments, are on the west side of a paved, flower-filled courtyard. To the south, the old monks' cells and a bathhouse are being restored (exploration at your own risk is usually permitted). The well-preserved church, built like so many others in Greece in the shape of a Greek cross, has a dome supported by four ancient Roman columns. Most of the frescoes are relatively late, dating from the 17th and 18th centuries; the distinctive bell tower is from the 19th century.
Reminder -- Kaisariani is still an active church. Remember to dress appropriately: Shorts, miniskirts, and sleeveless or skimpy shirts are considered offensive.