The townhall of King's Lynn has existed since the early fifteenth century, between 1422 and 1428,[13] when the Guildhall of the Holy Trinity was built. It is the most prominent feature of the townhall today with its steep arched roof, large window and chequered patterned exterior. The building was enlarged in 1624, when an extension with the same chequered style was added which now forms the main entrance to the townhall.