Wall recess to contain a beehive. Originally bees were kept in a woven basket known as a 'skep'.
Local examples (click to enlarge)
For bee boles in the Kent War Memorial garden click here
NOTE: The American Reverend L. L. Langstroth invented removable rectangular frames that hung downwards in the hive in 1862 - this proved more effective than the use of skeps in bee boles.