Capital: Kathmandu. Major Cities: According to the 2001 census, only Kathmandu had a population of more than 500,000. The only other cities with more than 100,000 inhabitants were Biratnagar, Birgunj, Lalitpur, and Pokhara. Independence: In 1768 Prithvi Narayan Shah unified a number of states in the Kathmandu Valley under the Kingdom of Gorkha. Nepal recognizes National Unity Day (January 11) to commemorate this achievement. Public Holidays: Numerous holidays and religious festivals are observed in particular regions and by particular religions. Holiday dates also may vary by year and locality as a result of the multiple calendars in use-including two solar and three lunar calendars-and different astrological calculations by religious authorities. In fact, holidays may not be observed if religious authorities deem the date to be inauspicious for a specific year.