The calendar was introduced by Nepal's Shah Kings, believed have migrated from India to Nepal during the middle age.
Bikram Era calendar is the official calendar of Nepal.
All government offices, private offices and educational institutions were closed to mark the Nepalese new year, which starts from mid-April.
People usually visit hill stations, organise parties, visit hotels and restaurants, go to picnic spots to celebrate the occasion and exchange greetings.
Major tourist hubs here, mainly Thamel, Durbarmarg and Hanumandhoka Durbar Square were jam-packed with tourists as well as Nepalese youths, who gathered there for celebrations.
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In his message Yadav, said: "Promulgation of the new constitution based on the values of federal democratic republic is our main priority at a time the Constituent Assembly (CA) and Legislature-Parliament have been established with the successful holding of the CA elections.
"It is the responsibility of all of us to make the people's aspirations result-oriented. The country needs peace and development," the President said, adding that extremism cannot "lure the Nepali people who have voted for peace and democracy".
"It is time for all national forces to stand in the same point for the protection and promotion of the achievements made so far," he said, and wished for successful writing of the new constitution representing people's aspirations.
"The remaining task of the constitution writing would be accomplished in the new year," he said, adding that "establishment of peace and rule of law would help expedite the development activities as roads, railway, airport, hydro powers.
"The New Year will not only be a historic year with the promulgation of the new constitution and institutionalisation of the federalism and republic achieved through the seven- decade-long struggle, but also becomes a turning point for economic prosperity for the country," said Koirala.