NileGuide Expert tip:
Shopping hours in Greece are peculiar. MW and Sat, you won't find much open past 6, and that's if they didn't close at 3. T,Th,F, they're open late but might close between 2-5 for siesta. Sundays most are closed.
Ermou is one long row of retail paradise named after the patron god of merchants and travelers, Hermes. It's a straight shot from Syntagma Square to Monastiraki Square, for the most part protected though delivery trucks and police cruisers will make pedestrian shoppers step to the side once in a while. Women crowd outside the windows of shoe stores like J.B. Bournazos. Kids tug their mothers into the Lego Store at 8 Ermou, while couples consult their partners' choices in department stores like Fokas, Zara, and Hondos Center. The chairs of the widespread cafes are usually half full in the connecting off streets; Diomias and Evangelistrias are two with ample choices, though diversity in the product varies little. Most of the cafes along Ermou all offer the same cofees, juices, and light snacks of mediocre quality for more than you will pay elsewhere. The idea is to enjoy a long period of sitting in the action.
Even if you're not a shopper it's an experience to walk the street during a "shopping day," whether Tuesday, Thursday, and Friday night. Balkan brass bands, living statues, and the oft heart-wrenching music of accordion soloists have all chosen their places along the sides to catch the attention of the well dressed crowds, usually feeling more generous as they came with the intention of spending money.
Easiest access is to take any bus that stops at Syntagma Square (A2, B2, 126, 106 are just a few that do) the tram, or the metro via the Red or Blue line (lines 2 &3) If you take the bus from the south (Plaka or the coast) get off at the stop outside of the National Gardens, just before Parliament and cross the street (carefully!)
For tips on using the metro, see the NileGuide local flavor blog article, The Wonderful, Marvelous, Metro of Athens.