WHAT lies beneath Clifford's Tower?

That's the question archaeologists hope to answer as part of an on-going investigation throughout this year looking at the historic tower and the mound on which it sits.

They hope to be able to better understand its archaeology and its structural stability.

A spokesman for English Heritage said: "What we learn and discover through these works will help us build a bigger picture about what could be done to improve the visitor experience at this increasingly popular York landmark."

The tower, which is almost all all that remains of York Castle, which was originally built by William the Conqueror, is closed for two weeks. On Tuesday a crane was used to lift borehole equipment into the tower as it was too large to go through the medieval doors.

The crane will return some time next week once the work is completed to retrieve the equipment.

The story of Clifford's Tower has been colourful and sometimes violent, and over the centuries the tower's mound, set in the heart of Old York, has been rebuilt many times, sometimes changing radically. In 1826 the lower slopes were removed and the mound was then circled with a stone wall. Later in 1935 the missing lower slopes were reconstructed and the stone wall buried within the mound.

Over the course of the 20th century little work was done to explore the physical make-up of the mound and its many archaeological layers.

The spokesman said: "English Heritage wants to offer visitors to Clifford's Tower an experience that does justice to the tower's history and its magnificent setting within the city.

"However, before we can start planning for the future, we need to better understand the tower's past. These works are an important part of this process. We will keep the public informed throughout, both on-site and online with tours, meetings, and regular updates."

Clifford's Tower is expected to re-open on Saturday, January 24.