According to the Valmiki Ramayana’s account, the vanara army took five days to build the bridge to Lanka. The bridge, commonly called Rama Setu, was constructed under the direction of Nala, who is described as the son of Vishvakarma, the divine architect.
In the Yuddha Kanda, the monkeys gather trees, logs, rocks and other materials and cast them into the sea. The poem gives a five-day progress report: fourteen yojanas on the first day, twenty on the second, twenty-one on the third, twenty-two on the fourth and twenty-three on the fifth. Together, these figures total one hundred yojanas.
The five-day figure refers to construction itself, not every event before Rama’s army reached Lanka. In the surrounding narrative, Rama first appeals to the ocean and eventually threatens to dry it before the bridge-building begins.
This episode should also be distinguished from the natural chain of limestone shoals between India and Sri Lanka, known today as Adam’s Bridge or Rama Setu. The epic’s bridge is a literary and religious account, while the geological origin of the modern shoals is a separate question.