By Fiona McKay

FOR years, Glaswegians used the Rotunda tunnels to make their way from one side of the Clyde to the other.

More recently, however, parts of this industrial thoroughfare have fallen in to bad disrepair with the South Rotunda in much worse condition than its twin on the north side of the river.

But now a major architectural upgrade has been finished on the building, which means it will be ready for use this month.

Architect Colin Anderson, who led the refurbishment, said the new work had kept the integrity of the building with a "long, distinguished and unique industrial history".

Originally designed by engineers Simpson and Wilson, both the North and South Rotundas were built between 1890 and 1896 to cover lift shafts to tunnels under the River Clyde.

The Glasgow Harbour Tunnel, as it was officially named, was opened in 1895 and housed three tunnels, each around five metres in diameter.

One was for pedestrians, while the remaining two carried carts and horse-drawn vehicles. Later cars were also able to use these tunnels.

They connected two areas, the North Rotunda near the SECC, and the South Rotunda which sits close to the STV studios at Pacific Quay.

Both of these round buildings covered 24 meter deep shafts containing hydraulic lifts and stairs to take users to and from the tunnels.

During the Second World War, the lift metalwork was removed for the war effort, and both tunnels remained closed in 1943 due to safety fears as there were frequent leaks from the river above.

The pedestrian tunnel was reopened in 1947 and remained in use until April 1980 and was later sealed and a large water main installed by Scottish Water in 1987.

That tunnel is still there (though closed to the public) but the two others were filled in in 1986.

The South Rotunda has been used on various occasions, including the Glasgow Garden Festival in 1988 and a pop-up theatre in 2014.

However, unlike the North Rotunda, which has been used as a casino, bar and restaurant hub, it has for the most part lain empty and fallen in bad shape.

The Grade B listed building was even put on the "at risk" register, but now after a two year project it has been restored to its former splendour.

Mr Anderson, of GD Lodge Architects, said the main challenge was converting the shelter to a habitable space.

He said: "It was never a building, it was an enclosure, so it was really an empty void when we first started."

Taking place over three stages, the first — the conservation stage — worked on the conditions on the outside of the building.

The second structural stage saw to the metalwork, floors and made sure it was water-tight, while the final fit-out stage made it fit for purpose for new owners, marine engineering firm Malin Group.

The build included the addition of five new windows, which Mr Anderson says are appropriate to the structure, and five floors including two levels within the old dome.

Mr Anderson says this the defining feature of the new building, which will include a gallery area on the highest floor.

He said: "The gallery at the dome is one of the most striking parts, as it brings you face-to-face with all the wrought iron on the upper level.

"Here the project as a concept has surpassed our expectations as it's really bringing you close to the industrial history which hasn't been seen before."

He added: "We're pulling it back from the brink, it wouldn't have lasted much longer without this work."