The image, captioned by Musk only with the words “Giga Berlin,” shows the huge assembly plant bathed in golden sunlight, its roof covered with solar panels and an apparent recreation area above the main entrance.

By mid-afternoon, the post had received more than 225,000 likes.

In response to queries, Musk tweeted remarks such as: “Might be an indoor/outdoor rave space on the roof.” He also indicated there would be a swimming pool.

The plant, which is currently under construction, is expected to assemble up to 500,000 vehicles a year and will open in July 2021.

It will house a pressing plant for vehicle body parts, a paint shop and a casting plant, along with a final assembly line.

Construction has begun, even though the final permits have yet to be granted. While local and national politicians have been enthusiastic, environmentalists have sought to block the building work.

The plant is expected to employ more than 10,000 workers.