Egypt has opened its 4,600-year-old "bent" pyramid to visitors, who can travel deep inside its tunnels to visit the chambers inside.

As of Saturday, visitors can walk through a 256-foot (78-meter) tunnel, down to two chambers inside the pyramid, Reuters reported.

The pyramid, built for Pharaoh Sneferu around 2,600 BC, looks different to Egypt's most famous pyramids, which have straight sides.

Instead, the angles of its sides change, giving it its bent appearance.

According to the BBC, the 331-foot (101-meter) pyramid was supposed to have the regular shape, but its creators had to make some adjustments as they were building on soft clay that didn't provide a stable foundation.

Mostafa Waziri, secretary general of Egypt's Supreme Council of Antiquities, told Reuters that cracks began to appear as a result while the pyramid was being built.

To compensate, they changed the angle from 54 degrees – the angle of a normal pyramid's sides – to 43 degrees.

Its shape is unusual, but it was an important step in the construction of Egypt's pyramids, bridging the gap between the earlier structures, which had stepped sides, and the later pyramids with their straight angled sides, like the Great Pyramid of Giza.

The bent pyramid is one of three pyramids that was built for Sneferu, though his burial place is not known.

Mohamed Shiha, director of the site that contains the pyramid, told Reuters that it is possible the Pharaoh is buried in the bent pyramid, and hasn't yet been discovered.

"Exactly where he was buried – we are not sure of that. Maybe in this [bent] pyramid, who knows?"

The pyramid has been opened for the first time since it was excavated in 1956 and comes as Egypt seeks to boost tourism, particularly to less-visited areas.

Visitors can also enter a 18-metre (59-feet) high "side pyramid", that was possibly built for Sneferu's wife, Hetepheres.

This article was originally published by Business Insider.