Greece's main highways to the north and the south link up in Athens; both are called Ethnikis Odos (National Road). Take the Attiki Odos, a beltway around Athens that also accesses Eleftherios Venizelos International Airport, to speed your travel time entering and exiting the city.
At the city limits, signs in English clearly mark the way to both Syntagma Square and Omonia Square in the city center. Leaving Athens, routes to the highways and Attiki Odos are well marked; signs usually name Lamia for points north, and Corinth or Patras for points southwest. From Athens to Thessaloniki, the distance is 515 km (319 mi); to Kalamata, 257 km (159 mi); to Corinth, 84 km (52 mi); to Lamia, 214 km (133 mi); to Patras, 218 km (135 mi); to Igoumenitsa, 472 km (293 mi).
Driving in Athens is not recommended unless you have nerves of steel; it can be unpleasant and even unsafe. It's fairly easy to get around the city with a combination of public transportation and taxis; save car rentals for excursions out of town. Red traffic lights are frequently ignored, and motorists often pass other vehicles while driving on hills and while rounding corners. Driving is on the right, and although the vehicle on the right has the right-of-way, don't expect this or any other driving rule to be obeyed. The speed limit is 50 kph (31 mph) in town. Traffic tends toward gridlock or heart-stopping speeding; parking in most parts of the city could qualify as an Olympic sport. Seat belts are compulsory, as are helmets for motorcyclists, though many natives ignore the laws. In downtown Athens do not drive in the bus lanes marked by a yellow divider; if caught, you may be fined.
Downtown parking spaces are hard to find, and the few downtown garages—including ones in vacant lots—are both expensive and perpetually full. The addition of parking meters and controlled parking zones at some point is expected to ease the situation in congested, high-traffic areas like Kolonaki, Syntagma, and Exarchia. Still, you're better off leaving your car in the hotel garage and walking or taking a cab. Gas pumps and service stations are everywhere, and lead-free gas is widely available. Be aware that all-night stations are few and far between.