Siddhartha Gautama was born around 623 B.C. He grew up in his father's luxurious palace in the city of Kapilvastu. He was forbidden by his father to leave the palace for the first 29 years of his life, thus he was never exposed the sufferings of life. As soon as he left the palace he saw the four sights, which prompt him to immediately leave his luxurious life behind and become an ascetic in order to find the end of human suffering.
It has already been 2,500 years since the life of Buddha and since then there has been lots of confusion and no clear records on this matter. The only written account we have of where Kapilvastu is is from Huen Tsian, a Chinese scholar who travelled to India in search of Buddhism during the 6th century AD. The search for Kapilvastu began during the mid-19th century AD, when they finally managed to translate Huen Tsian's recount.
"Monasteries and stupas are built over the ruins of the royal precincts.”
As you can tell the description is pretty vague so it's very hard to be sure exactly where it is.
“Engulfed in complete darkness, the scholars made a beginning in the direction of locating Kapilavastu like a wild-goose chase,” K. M. Srivastava
History of Piprahwa
January 1898, William C Peppe made a shocking discovery of a stupa buried under his estate in Piprahwa, India. In the 1970s, Srivastava, an archaeologist excavated the site again. He found an additional stupa with 4 monasteries surrounding it on either sides. Within the stupa, a casket containing terra-cotta seals and other relics was uncovered. On one such relic “sukiti bhatinam sabhaginikanam sa puta dalanam iyam salila nidhane buddha bhagvate sakiyanam” was inscribed in Brahmi. It translates to- brothers, sister, kinsmen and successors hereby bury the relics of Buddha. All of this led some people to firmly believe this is the secret site of Kapilvastu, since there are monasteries and stupas just like in Huen Tsian’s recount.
There was only one problem, there's absolutely no evidence of a palace structure at Piprahwa at any point in history. This proved to be quite a significant problem because Buddha most definitely lived in a palace. However the Indian archeologists have found an explanation- right next door to Piprahwa is the site of Ganwaria which coincidently contained a palace structure. Perhaps these two sites were both part of Kapilvastu back in the past before getting labeled as two separate sites in modern day India.
History of Tilaurakot
Tilaurakot is close to Lumbini- a very important Buddhist pilgrimage site. An Ashoka pillar was found at Lumbini, the inscription confirms that is the birth place of the Buddha. Asoka pillars were built by Emperor Ashoka in 249 B.C. to promote the spread of Buddhism after he became a Buddhist. This led archeologists to think the palace is very close by.
Debala Mitra led an unsuccessful expedition in the 1960s at Tilaurakot, the team soon gave up when they came across a brick structure that was built hundreds of years after Buddha would have lived there. Having said that, recently another team supported by Unesco went back to the site, cut through the brick structure to reveal an original clay palace wall within that matched the time period. The evidence of Kapilvastu was further proved by cylindrical depressions found underneath the ground indicating the places where timber fence posts use to stand. Those were dated to at least 2,800 years ago, a time when Buddha would have been living in the palace. Other parts of an ancient city-houses, roads, walls and wells were also uncovered.
Tilaurakot is the official birth place of the buddha verified by the UNESCO World Heritage Center.
The archaeologist’s team comprised mainly of 10 professors from Stirling University and Durham University of the United Kingdom, two Unesco consultants, five experts from the DoA and four from the Lumbini Development Trust.