Co Loa

The most ancient capital of the Red River delta region. Visits by foreign tourists are almost unheard of, though the place is close enough to Hanoi that if you're interested in history it's definitely worth a trip.

By bus

There are frequent (and very cheap) buses from the Mỹ Đình bus station in Hanoi (see: Tuyến 46 Bến xe Mỹ Đình - Cổ Loa.
Buses running at least 20 hr every 20 minutes or so.
Price: 6,000 đong.

By train

Although it is not the most convenient, it is possible to go from Hanoi to Cổ Loa by train, using train 91 from Hà nội to Lào Cai. Since there is only one train a day in both directions, the best is to go by train, and come back by bus.
The advantage of going by train is to run on the beautiful Eiffel bridge on the Red River in Hanoi, and see beautiful landscapes on the way to Cổ Loa.
The train station of Cổ Loa is not in the Cổ Loa citadel. Hence, this requires an additional walk of 30-45 minutes through the country side and the fields. But this is worth the walk if you are not in a hurry!
Train schedule (source):

• Hanoi - Cổ Loa: 14:35 from the Long Biên train station in Hanoi, arriving at 15:16 in Cổ Loa.
• Cổ Loa - Hanoi: morning train

Price: 11,000 đong one way (as of 2013).

By bus or car

While it is possible to visit Cổ Loa by public bus from Hanoi, you would do better to hire a motorbike (or car).
Just head east out of town across the Red River bridge, then keep going straight. Turn left (i.e., north) immediately after driving up a slope and crossing a bridge over a second body of water distance later. Heading north, look carefully for a Cổ Loa sign on your right-hand side. (easier with GPS and a smartphone; or ask someone)

The best is to walk. Most temples are less than 20 minutes from the bus station.
If you want to go further, you may need a vehicle to explore the surroundings.

• Cổ Loa Museum (apparently free) stands at the main intersection just north of the bus station on the southern edge of the former citadel. This shows you the time periods you're dealing with, and the historic layout of the area. The context provided isn't so good, and not everything is translated, plus some of the objects on display are replicas. If you use your imagination it's pretty interesting though.
• There are two temples, one with a large circular body of water in front of it at which boat races are held at festival time also featuring some historic stelae written in Chinese characters, and one which is a sort of village Buddhist center. Both are of some significant vintage, but neither date from the period of the ancient city. Both charge nominal amounts for entry.
• The ancient earthen walls are still preserved and form a couple of concentric rings around the center of the town. Little temples on the walls are named after various historic gates ('southwest gate'), etc.
• Look out for the fields under plough by water buffalo: just as 2200 years ago when the town rose to prominence!
• There's some tombs about, but none visually interesting.

There are a few coffee and soft drink vendors are dotted around the middle of town and the bus station.
There are also some usual food stalls around the small city, including a market just opposite the bus station (south of the small city).

There do not appear to be any hotels in the town.

There do not appear to be any businesses offering Wi-Fi Internet access in the town.