Ajahn Sumedho was ordained as a Buddhist monk at Wat Mahathat in Bangkok, Thailand in 1967. This temple is one of the oldest and most important in Thailand, dating back to the 14th century. It is the headquarters of the Mahanikai sect of Theravada Buddhism and has a long history of producing highly respected and influential monks.

At the time of his ordination, Ajahn Sumedho was known as Robert Jackman. He had been raised in Seattle, Washington in a Methodist family and had a successful career as a jazz musician and university professor. However, he felt unfulfilled and began searching for a deeper meaning in life. This led him to explore different spiritual traditions, including Zen Buddhism and Sufism.

In 1966, he traveled to Thailand and met Ajahn Chah, a highly respected and influential Buddhist monk. After spending some time with him, Ajahn Sumedho decided to become a monk and was ordained the following year. He was given the name Sumedho, which means "one who has a good heart" in Pali, the language of the Theravada Buddhist scriptures.

Ajahn Sumedho spent the next decade studying and practicing Buddhism in Thailand, including spending several years in intensive meditation retreats in the forest. In 1975, he was invited by Ajahn Chah to help establish a monastery in England. This became the first branch monastery of Wat Pah Pong, the forest monastery in Thailand where Ajahn Chah was the abbot.

Under Ajahn Sumedho's guidance, the monastery, now known as Amaravati, grew into a thriving community of monks, nuns, and lay practitioners. Ajahn Sumedho's teachings and approach to Buddhism, which emphasized mindfulness and simplicity, resonated with many Westerners and helped to popularize Theravada Buddhism in the West.

In 1984, Ajahn Sumedho was appointed the abbot of Chithurst Monastery, another branch monastery in England. He continued to teach and lead retreats around the world, and his teachings were compiled into several books, including "The Four Noble Truths" and "The Mind and the Way." In 2002, he retired as abbot and moved to New Zealand, where he continues to teach and write.

In summary, Ajahn Sumedho was ordained as a Buddhist monk at Wat Mahathat in Bangkok, Thailand in 1967. His spiritual journey and teachings have had a profound impact on the spread of Theravada Buddhism in the West and continue to inspire many to this day.