Downtown Athens is a shoppers paradise. Besides the areas of the Plaka and Monastiraki which are well known to travelers for their large variety of tourist shops all of central Athens is a shopper's Mecca. Streets that were once choked with traffic have now been closed to all motor vehicles and this diverse shopping area has become a walking shoppers paradise with every kind of shop you can imagine, and some you never imagined existed. There are street merchants selling everything from scarves to devices that make stuffed grape leaves or hollow out a zucchini. The clothing shops have quality men and women's apparel from all over the world and the shoe stores make you wonder why your choices at home are so limited. Check out Spiliopoulos towards the bottom of Ermou where I buy my shoes. It is like a shoe-free-for-all that can be like the NY Stock Exchange during a buying frenzy. If you go to the end of Ermou and turn right on Athinas Street there are a number of clothing shops where you can find more casual stuff, jeans, T-shirts and these wild Polynesian shirts that I am not allowed to get because they make me look like I weigh 300 pounds (according to my wife). Speaking of weight there is a clothes shop on Athinas street between Ermou and Agia Erinis with clothes for big people. Really big people. On the same street you can buy cool souvenir shirts, not like the ones they sell in the flea market or the Plaka. The kind that even Greeks buy. Soccer jerseys of local teams and heroes, Greek police and military shirts and even American sports team shirts that were obviously made by someone who did not know anything about the sport and barely spoke English. (I am still upset that I did not buy the Daryl Blackberry baseball shirt I saw a few years ago. What was I thinking?) Other examples are sweatshirts of well-known colleges and universities with mis-spelled words including Univercity. 

In Syntagma Square there is a giant computer-video-CD-DVD-electronics shop called Public. Its like a Best Buy only with lots more stuff and it is housed in a restored 19th century mansion. If you are a computer guy like me or you want to let your wife check out the clothing shops on Ermou while you do something important like check out the new laptops I think you will be impressed with this place. 
In America when someone wants to open a shop of any kind, the first thing he looks to see if there is any competition in the neighborhood that may hurt his chances at success. In downtown Athens it is the opposite. You can find an entire block of stores, one after the other that sell doorknobs. Every doorknob known to mankind from ancient to modern times on display. So when someone is building a house and it's time to put in the doorknobs, they know that if they go down to Vissis street (off Athinas Street), one of the many doorknob shops will have what they are looking for. if they are looking for lights they go to the district where all the lights are on Vouliagmenis street. If they want furniture they go to that district.
If someone is looking for quality shoes or clothes they will go down to Ermou street, the number one shopping street in Athens where besides local shops you can find well known stores like Benneton, Zara's and other international shops. There is even a Bodyshop. Ermou at one time was a main street for traffic. It is now one of the largest of Athens streets to be closed to cars and it is like a New York City street fair, any day of the week, with thousands of shoppers, street musicians and people selling hot chestnuts in the winter and corn-on-the-cob in the summer. It's like a high-class bazaar. 
(For women looking for fabric and other dressmaking supplies on the north side of Ermou near Syntagma, is Καλυβιωτης (Kaliviotis). They also sell fabric, silk flowers, all kinds of tailoring supplies, buttons, costumes, and God only knows what.   Very cool for seamstresses... it is full of French women!  They had Butterick, Burda, McCall and Vogue pattern books to choose from... current ones!).
The two other main shopping streets of Eolou and Agiou Marou are the streets where you can find incredible bargains in clothes, fabrics, yarn, shoes, and cafes where you can catch your breath after a period of furious shopping. There are old women from Russia and young men from Persia, selling silk shirts, socks, and underwear on the street. While in the area don't forget to visit the Athens Central Market. You probably won't be in the market for any meat or fish but you can buy some fruit, olives or nuts for your room. If you go down Evripidou Street and cross Athinas street you will come to an area that is the Athenian Eqiuvelant of China town. Or maybe its India-Pakistani town? Or the nearest 
Middle-east? Whatever you want to call it, the neighborhood is full of small Chinese import shops, the excellent Elixer Herb Shop (on vripidou), plant shops, dry goods and who knows what else?
In August-September and January-February everything is on sale. You can literally go to Greece and replace your wardrobe and the 
money you save will pay for your ticket. To find Ermou street just go to Syntagma Square where it begins at the McDonalds. 
Eolou begins at Adrianou at Platia Agoras (the square that has been taken over by restaurants and cafes) and crosses Ermou just below the church of Kapni Karea in the middle of the street. It goes almost all the way to Omonia and passes the Central Market and the giant square in 
front of town hall. There is always something going on at Aeolou and Ermou streets. There are musicians and dancers and thousands of 
shoppers. Sometimes it is more fun to look at people than the shops. And if you are lucky and you pass the small Church at Kapni Karea you may even see an angel.
Remember that  the shops open in the morning and stay open until 9pm except on Monday and Wednesdays and Saturdays when they close at around 2:30. Generally shops are closed on Sundays, but that's the day to go to the Flea Market in Monastiraki. Keep your eyes open when shopping in Athens. Not every shop has a big glass window with their goods displayed on the sidewalks. Some shops are hidden away in alcoves, atriums, basements and even the backs of apartment buildings. In fact many of the true craftsmen have shops that seem like they are hidden, either because they have a circle of customers that keep them busy enough or because they are artists happy with the way things are and don't seek more business. An example would be Harris the Beltman, who makes beautiful handmade belts in the back of an apartment building at 21 Nikis st in the Plaka. (He is also a licensed skipper if you happen to need one)
And after a busy day of shopping and walking through museums and archaeological sites what could be better than to get a nice food massage? And who better to give that massage but thousands of little fish! You can do this at the Athens Fish Spa at 45 Aeolou Street. What is a Fish Spa? It's a place where you put your feet in a fish tank and these little teethless feet nibble away the dead skin. What does it feel like? It feels like thousands of little fish nibbling your feet, which is to say it feels pretty darn good. As the shop says on its website: "Your feet will feel amazing, refreshed and healthy. These clever fish can also stimulate acupuncture points helping to rejuvenate the nervous system, relax the body and release fatigue. Your blood circulation and flow is also greatly increased during the treatment."  To find the Athens Fish Spa from Athinas Street, walking towards Omonia turn right at the Municiple Police Station, across the street from the Hotel Attalos and walk up Boreous Street and turn left on Aeolou.
Source: http://www.athensguide.com/shopping/index.html

Athens Concert Hall

Egg Donation

Vouliagmeni Lake