On 8 June 2016, the world's longest-reigning monarch, Thailand's 88-year-old King Bhumibol Adulyadej, marks the 70th anniversary his taking of the throne.

He was born in Cambridge, Massachusetts, on 5 December 1927, while his father was studying at Harvard. His father died when he was less than two years old, and when his childless uncle abdicated in 1935, his nine-year-old brother Ananda became King of Thailand. The family lived in Switzerland until the end of the Second World War. On 9 June 1946, his brother King Ananda died of a gunshot wound under mysterious circumstances, making the 18-year-old Bhumibol King of Thailand, though he was only crowned on 5 May 1950, a week after marrying Mom Rajawongse Sirikit Kitiyakara, daughter of the Thai ambassador to France.

Thailand King Bhumibol Adulyadej
1929: Mom Sangwal Mahidol na Ayudhya with her children Prince Bhumibol Adulyadej (centre), Prince Ananda Mahidol and Princess Galyani VadhanaBureau of the Royal Household, Kingdom of Thailand
Thailand King Bhumibol Adulyadej
1945: Bhumibol Adulyadej with Princess Mother Sri Sangwal and Princess Galyani Vadhana at the Villa Vadhana, their private residence in Lausanne, SwitzerlandBureau of the Royal Household, Kingdom of Thailand
Thailand King Bhumibol Adulyadej
5 May 1950: King Bhumibol is pictured during his coronation at the Royal Palace in BangkokUnknown
Thailand King Bhumibol Adulyadej
1946: A portrait of King Bhumibol AdulyadejUnknown
Thailand King Bhumibol Adulyadej
19 July 1960: King Bhumibol Adulyadej and wife Queen Sirikit Kitiyakara pose with Queen Elizabeth II and Prince Philip, Duke of Edinburgh at Buckingham Palace in LondonGamma-Keystone via Getty Images
Thailand King Bhumibol Adulyadej
12 October 1960: French President General de Gaulle and his wife Yvonne pose with Thailand's King Bhumibol Adulyadej and his wife queen Sirikit at the Elysee Palace in ParisAFP
Thailand King Bhumibol Adulyadej
8 August 1988: Thailand's King Bhumibol Adulyadej is visited by Britain's Prime Minister Margaret Thatcher at Chitralada Palace in BangkokReuters
Thailand King Bhumibol Adulyadej
28 October 1996: Royal guards shade Queen Elizabeth II and King Bhumibol Adulyadej from the sun during a welcoming ceremony at Bangkok military airport during the British royals' five-day visit to commemorate the 50th anniversary of the Thai king's accession to the throneReuters
Thailand King Bhumibol Adulyadej
25 November 1996: King Bhumibol Adulyadej shakes hands with US First Lady Hillary Rodham Clinton as President Bill Clinton looks on during their meeting at Chitrlada Palace in BangkokReuters
Thailand King Bhumibol Adulyadej
8 May 1998: King Bhumibol Adulyadej takes pictures during the royal ploughing ceremony in BangkokPornchai Kittiwongsakul/AFP
Thailand King Bhumibol Adulyadej
Thailand King Bhumibol Adulyadej
4 November 1999: King Bhumibol Adulyadej sits on the Royal Barge during a procession on the Chao Phraya River in Bangkok to celebrate his 72nd birthdayReuters
Thailand King Bhumibol Adulyadej
5 December 1999: King Bhumibol Adulyadej, Crown Prince Maha Vajiralongkorn and Queen Sirikit appear on a balcony of Anantasamakom Throne Hall to mark the king's 72nd birthdayPornchai Kittiwongsakul/AFP
Thailand King Bhumibol Adulyadej
5 August 2002: Hundreds of Buddhist Monks pray for the health of Thailand's king inside the Temple of the Emerald Buddha at the Grand Palace in Bangkok. Bhumibol Adulyadej, 74, the world's longest-reigning monarch, spent time in hospital recovering from a hernia operationReuters
Thailand King Bhumibol Adulyadej
19 October 2003: US President George W Bush toasts with Thailand's King Bhumibol Adulyadej as they take part in a State Dinner at the Royal Grand Palace in BangkokJason Reed/Reuters
Thailand King Bhumibol Adulyadej
22 October 2003: Russian President Vladimir Putinand his wife Lyudmila pose with Thai King Bhumibol Adulyadej and Queen Sirikit at the Grand Palace in BangkokGrigory Dukor/Reuters
Thailand King Bhumibol Adulyadej
9 March 2005: Thai Prime Minister Thaksin Shinawatra prostrates himself before a picture of Thai King Bhumibol Adulyadej after receiving the royal commandReuters
Thailand King Bhumibol Adulyadej
2 December 2005: Thai royal guards in colourful uniforms march during a celebration to commemorate King Bhumibol Adulyadej's 78th birthday at the Royal Plaza in BangkokSaeed Khan/AFP
Thailand King Bhumibol Adulyadej
12 June 2006: The Royal Barge procession cruises down the Chao Praya river in Bangkok, to celebrate the 60th anniversary of King Bhumibol Adulyadej's accession to the thronePaula Bronstein/Getty Images
Thailand King Bhumibol Adulyadej
12 June 2006: Thailand's Crown Prince Maha Vajiralongkorn greets Britain's Prince Andrew as King Bhumibol Adulyadej and Queen Sirikit look on at Ananda Samakhom Throne Hall in Bangkok, during the Thai monarch's Diamond Jubilee celebrationsReuters
Thailand King Bhumibol Adulyadej
12 June 2006: Thailand's King Bhumibol Adulyadej sits with all his royal guests at Ananda Samakhom Throne Hall in Bangkok during his Diamond Jubilee celebrationsGetty Images
Thailand King Bhumibol Adulyadej
20 July 2006: Volunteers take away a woman who fainted as Thailand's King Bhumibol Adulyadej arrived at the Siriraj hospital to be admitted for spinal surgerySaeed Khan/AFP
Thailand King Bhumibol Adulyadej
20 July 2006: King Bhumibol Adulyadej checks his camera settings to take a picture of his well-wishers gathered at Siriraj Hospital in Bangkok as he arrives to undergo surgery on his spineSaeed Khan/AFP
Thailand King Bhumibol Adulyadej
4 August 2006: Thailand's King Bhumibol Adulyadej comes out to see his well-wishers in a wheelchair as he leaves Siriraj Hospital in Bangkok, after successful spinal surgeryAFP
Thailand King Bhumibol Adulyadej
2 December 2006: King Bhumibol Adulyadejreviews a parade with Queen Mom Rajawongse Sirikit to mark his 79th birthdayChaiwat Subrasom/Reuters
Thailand King Bhumibol Adulyadej
7 November 2007: Thailand's King Bhumibol Adulyadej leaves the Siriraj hospital in Bangkok, after suffering a blood clot in his brainChumsak Kanoknan/ Getty Images
Thailand King Bhumibol Adulyadej
9 November 2007: A woman buys a pink T-shirt at a market in Bangkok. Thais started wearing pink, believing the lucky colour would bring a fast recovery to their monarchChaiwat Subrasom/Reuters
Thailand King Bhumibol Adulyadej
20 October 2008: Thai King Bhumibol Adulyadej and Queen Sirikit hold hands during a pre-funeral ceremony for his late sister Princess Galyani Vadhana in BangkokAdrees Latif/Reuters
Thailand King Bhumibol Adulyadej
5 December 2009: King Bhumibol Adulyadej waves to a crowd of well-wishers as he leaves the Siriraj Hospital to attend a ceremony at the royal palace to mark his 82nd birthdayChristophe Archambault/AFP
Thailand King Bhumibol Adulyadej
29 September 2010: Thailand's revered King Bhumibol Adulyadej goes for a concert at Siriraj Hospital in BangkokDamir Sagolj/Reuters
Thailand King Bhumibol Adulyadej
8 August 2011: Thailand's first female Prime Minister Yingluck Shinawatra prostrates herself before a portrait of King Bhumibol Adulyadej, as she receives the royal commandRungroj Yongrit/AFP
Thailand King Bhumibol Adulyadej
5 December 2011: Thailand's King Bhumibol Adulyadej leaves Siriraj Hospital for the Grand Palace in BangkokDamir Sagolj/Reuters
Thailand King Bhumibol Adulyadej
18 November 2012: US President Barack Obama, with Secretary of State Hillary Rodham Clinton and Ambassador Kristie Kenney, meets with King Bhumibol Adulyadej of the Kingdom of Thailand, at Siriraj Hospital in BangkokOfficial White House Photo by Pete Souza
Thailand King Bhumibol Adulyadej
5 December 2012: Thailand's King Bhumibol Adulyadej makes a rare public appearance on his 85th birthdayAthit Perawongmetha/Getty Images
Thailand King Bhumibol Adulyadej
5 December 2014: Military cadets attend a ceremony celebrating the birthday of Thailand's King Bhumibol Adulyadej outside the Grand Palace in Bangkok. He cancelled a public appearance on his 87th birthday on the advice of doctors, disappointing thousands waiting outside the hospital where he is staying, hoping for a glimpse of the world's longest-reigning monarchDamir Sagolj/Reuters
Thailand King Bhumibol Adulyadej
10 May 2015: Thailand's King Bhumibol Adulyadej leaves Siriraj Hospital in Bangkok after seven months spent convalescing following surgeryChaiwat Subprasom/Reuters
Thailand King Bhumibol Adulyadej
5 December 2015: A woman cries as she looks up at the hospital room of the ailing King Bhumibol Adulyadej at Siriraj hospital in Bangkok, on his 88th birthdayPaula Bronstein/Getty Images
Thailand King Bhumibol Adulyadej
8 June 2016: Bank employees sort new 70 Baht banknotes printed by the Thai Central Bank to commemorate King Bhumibol Adulyadej's 70 years on the throneAthit Perawongmetha/Reuters

Two days before the 70th anniversary of King Bhumibol Adulyadej ascending to the throne, he underwent an operation to clear an artery. The Royal Household Bureau said the procedure to insert a stent was conducted with satisfactory results after tests determined that there was an inadequate supply of blood to the muscles of his heart.

In the past month, the king has also been treated for a build-up of fluid surrounding the brain and a swollen lung. The king's health is a matter of intense national concern because of uneasiness about political stability during the succession. He has been hospitalised for much of the past decade.

News about the royals is tightly controlled in Thailand, where laws protecting the royal family from insult make it a crime to defame, insult or threaten the king, queen, heir to the throne or regent. The military generals who took power in a May 2014 coup have been cracking down on critics of the monarchy, ramping up prosecutions and handing down record sentences for those found guilty.