“In the Indian state of West Bengal lies a district known as Cooch Behar which is curiously merged with its neighbor, Bangladesh. The Indian land contains 92 Bangladeshi enclaves, and the Bangladeshi land contains 106 Indian enclaves. The largest Indian enclave itself contains a Bangladeshi enclave, and that Bangladeshi enclave contains a bare hectare of Indian farmland known as Dahala Khagrabari. That makes Dahala Khagrabari the world’s only instance of an enclave in an enclave in an enclave.”

http://www.futilitycloset.com/2013/11/16/well-bounded/

see also List_of_enclaves_and_exclaves