Shrewsbury is the county town of Shropshire, set within an almost complete loop of the River Severn, which gives it both a distinctive topography and a natural defensive character that shaped its medieval development. The town is renowned for its exceptional concentration of black-and-white timber-framed buildings, narrow mediaeval passageways ('shuts'), and landmarks including Shrewsbury Castle, Shrewsbury Abbey and St Chad's Church. It is also celebrated as the birthplace of naturalist Charles Darwin and hosts the world-famous annual Shrewsbury Flower Show.