Who built the harmandir sahib?

The Harmandir Sahib, also known as the Golden Temple, was built by Guru Ram Das, the fourth Sikh Guru.

While the initial foundation was laid in 1577 by Guru Ram Das, the construction was completed by his successor, Guru Arjan, the fifth Sikh Guru, in 1604.

It's important to note that the temple has undergone several renovations and expansions over the centuries, but the core structure remains the same.