Colchester is full of history, but unlike many ancient towns it isn't all locked away in museums and behind fences. In just a brief walk around the town you can see everything from Roman times to the present day. As it's not on many regular tourist trails, it's a nice place to visit without being swamped in crowds of tourists.
Take some time to just walk around the town centre and nearby Dutch Quarter and you'll see some very old buildings and structures around. Check what's on at the Arts Centre and Mercury Theatre - both have very good and varied bills.
Head out of the town into the other parts of North Essex to see the scenery plus some typical sleepy English villages.