I've visited Colchester a few times since I've arrived in the UK. It only takes about ten minutes by bus to get into the center of the town from campus. A few days ago I stopped to admire the thousand year old castle in town...
This is Colchester Castle. It is now a museum, and it sits in a nice park right near the center of town.
The castle was built at the beginning of the twelfth century, and is the biggest keep (a type of castle) ever built by the Normans in Europe!
As you can see, the castle is under renovation. I'll be sure to visit again when it reopens in the spring.