Chandigarh, Nov 23: Thousands of devotees thronged gurdwaras across Punjab, Haryana, Himachal Pradesh and Chandigarh on Friday to offer prayers on the occasion of 'Gurpurab' - the 549th birth anniversary of the founder of Sikhism, Guru Nanak Dev.It also marks the start of the year-long celebrations leading to the 550th birth anniversary of Guru Nanak Dev (1469-1539) next year.The holiest of Sikh shrines Harmandir Sahib, popularly known as Golden Temple in Amritsar and other gurdwaras elsewhere saw religious fervour to mark the occasion. Long queues of devotees could be seen waiting to offer prayers inside the sanctum sanctorum.People braved the early morning chill to offer prayers at gurdwaras. Guru Nanak Dev was born in 1469 in Nankana Sahib town (now in Pakistan), around 80 km west of Lahore city.Reports of Gurpurab celebrations were received from Nankana Sahib also.Over 3,000 Sikh devotees have gone to Pakistan to celebrate at Nankana Sahib.Tight security arrangements were made around all leading Sikh shrines in Punjab in view of recent terror-related incidents in the state.The Golden Temple complex was decorated with lighting since Diwali and Bandi Chhor Diwas earlier this month. Hymns were being rendered at the holy shrine and scores of other gurdwaras across the region to mark the occasion. At other gurdwaras in cities, towns and villages, hundreds of people could be seen coming to offer prayers. 'Langars' (community kitchen) were arranged at most gurdwaras.Punjab Governor V.P. Singh Badnore and Chief Minister Amarinder Singh greeted people on the occasion and urged them to follow the Guru's teachings and to maintain peace and harmony.