Mumbai is historically known as the 'City of Seven Islands' because it was originally formed by seven separate islands: Bombay Island, Colaba, Old Woman's Island, Little Colaba, Mahim, Parel, and Mazgaon. These islands were gradually connected through reclamation and landfills to form the present-day Mumbai. Shimla is a hill station, Coorg is a coffee region, and Munnar is a tea plantation area - none of these are associated with islands.