The sixth-century collapse of Yemen's Maerib Dam has long been marked as an event that brought down an ancient commercial empire in the south-west corner of the Arabian Peninsula.
The breach of the dam is mentioned in the Quran, and the ruins of the architectural and engineering wonder have drawn visitors for centuries.
In 1982, Sheikh Zayed, Founding President of the UAE, signed an agreement with the Yemeni president, Ali Abdullah Saleh, offering to provide funds for rebuilding the dam.
"The dam was significant to him, as it is to many Arabs, not only for the history it represents but for the resources it had once provided and could provide again for agriculture and other uses," said Aqeel Ahmad Aqeel, a historic building conservator with the Abu Dhabi Authority for Culture and Heritage.
Sheikh Zayed asked for more than 900 kilometres of new canals to be added to the dam, offering Dh275 million (US$75m) for the rehabilitation project, which was completed eight months ahead of schedule in December 1986.
"For Yemeni people, it was a very precious gift from him to them," Mr Aqeel said. "They have been able to benefit from the preservation and use the water to care for their farms and their houses."
* Erin Conroy