A breathtaking view into the hidden depths.

A shaft on the Nenthead site is a link to one of the strangest and least known man-made features in the North-East.

The 382ft deep Brewery Shaft is connected to the Nent Force Level, a tunnel which was excavated at the bottom of the Nent Valley and which runs for four and a half miles underground to the town of Alston.

Begun in 1776, it took 63 years to complete and cost pounds 81,000.

The Brewery Shaft is the last of nine shafts down to the Nent Force Level.

It is enclosed by a building and surrounded by a viewing platform.

A press of a button and the room is plunged into darkness. Another button and a string of lamps lining the shaft are switched on to give a breathtaking view into the depths.

The Nent Force Level was driven to find new mineral veins and also to drain the mines in the area. Only one money-making vein was found.

By the early years of the 19th Century the flooded tunnel had become something of a visitor attraction. Thomas Sopwith, who lived and worked in Alston from 1824, wrote of the Nent Force Level:

"It is navigated in boats 30ft in length which are propelled by means of sticks projecting from the sides of the level and thus may be enjoyed the singular novelty of sailing a few miles underground and beholding in perfect safety the various rocks and the numerous veins which it intersects.

"As a number of candles are usually taken up, a variety of beautiful effects may be produced be leaving short pieces of them burning at intervals.

"The reflection of them in the water presents a fine spectacle and some idea is afforded of the vast extent of the level by the receding vista of lights."

Mackenzie's History of Northumberland of 1825 states: "The level of Nent Force is a stupendous work. Strangers may be accommodated with boats and guides by application at the Lowbyer Inn near Alston.

"Those who have the curiosity of taking a subterranean sail must be highly satisfied with the singularity of the scene. When accompanied by a band of music, the effect is beyond description."

In 1881, a book called North Country Sketches by Newcastle's John William Allan was published.

Allan toured the northern counties, writing as he went, and persuaded two brave souls from Alston to take him into the Nent Force Level in a boat with candles stuck to the sides and accompanied by a howling bulldog. Allan wrote: "We seemed to be so far away from things of the earth and were ploughing through its very bowels.

"There must have been enormous quantities of carbonic acid gas gathered and this, with the absence of oxygen, caused a feeling of great drowsiness."