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.
Get in and out
You can visit Co Loa by public bus number 17 from Hanoi. It costs 9,000 VND and takes about half an hour. It is the bus to the airport (Noi Bai) and runs every 10-15 minutes. The bus crosses the Red River out of Hanoi and continues up Highway QL1 before turning left onto Highway QL3. Then it turns right onto the smaller road that goes through Co Loa. The stop you want is the second one on this smaller road.
You could could alternatively hire a motorbike (or car). Just head east out of town across the Red River bridge, then keep going straight. Turn left (ie. 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 Co Loa sign on your right-hand side. (The whole thing is easier with GPS and a smartphone; or ask someone!)
You really need a vehicle to explore the surroundings.
See and Do
Eat and Drink
There are some street food type venues but if you need Western food you might want to eat before leaving Hanoi. A few coffee and soft drink vendors are dotted around the middle of town and the bus station.
There do not appear to be any hotels in the town.
There do not appear to be any businesses offering wifi internet access in the town.