Southwark is a district of Central London situated on the south bank of the River Thames, forming the north-western part of the wider modern London Borough of Southwark. The district, which is the oldest part of South London, developed due to its position at the southern end of the early versions of London Bridge, the only dry crossing point for many miles. Around 43 AD, engineers of the Roman Empire found the geographic features of the south bank suitable for the placement and construction of the first bridge.