Ipswich is the county town of Suffolk and one of the oldest continuously inhabited towns in England. It sits at the head of the Orwell estuary, and the waterfront — once the beating heart of a major medieval wool port — has been reinvented as the Waterfront quarter, with converted warehouses, restaurants, and a marina where container ships used to dock.
The town's medieval prosperity is still visible in its street plan and in the dozen or so surviving medieval churches — more than almost anywhere else in England outside London and Norwich. St Peter's and St Mary at the Elms are worth a look if old flint churches are your thing. The Christchurch Mansion, a Tudor manor house set in a large park, holds a remarkable collection of Gainsborough and Constable paintings, both of whom grew up nearby. It's free and often quietly wonderful.
Ipswich has had a rougher ride than its neighbour Bury St Edmunds since deindustrialisation, and parts of the town centre are undeniably scruffy. But the Waterfront regeneration has brought real energy, the local football club (Ipswich Town) generates fierce civic pride, and the market town culture of Suffolk bleeds in at the edges — good food, good produce, not much pretension.
It makes a decent base for exploring the Suffolk coast, the Dedham Vale, and the wool towns of the Stour Valley. Constable Country is practically on the doorstep.