When did the construction of the grand Palace in the Bangkok start?

When did the construction of the grand Palace in the Bangkok start?

Explanation

The Grand Palace complex was established in 1782.

It consists of not only royal and throne halls, but also a number of government offices as well as the renowned Temple of the Emerald Buddha.

It covers an area of 218,000 square metres and is surrounded by four walls, 1900 metres in length.