st denys' church, sleaford is a medieval church located in sleaford, lincolnshire, england. the oldest parts of the present building are the tower and spire. the spire stands 144 feet (44 metres) tall. a window tracery is dated to about the late 13th century. the gothic nave, aisles and north transept were built in the 14th century. the church is a grade i listed building, a term given to "buildings of exceptional interest".