The end for Horseshoe Bridge tower

It has been called a cultural icon and a commercial horror but the prominent Horseshoe Bridge advertising tower is within hours of demolition after more than 100 years.

On Monday, it will be pulled down for the Perth City Link project.

The tower started life in 1896 as a 25,000 gallon (114,000 litre) cast-iron water tank and stand to support Perth's growing train network.

Jeff Austin, from Rail Heritage WA, said the stands were usually wood not steel, which was probably considered to look better and be easier to maintain.

"The stand may have been moved slightly to accommodate the Horseshoe Bridge in 1904 but it is essentially in the same spot," Mr Austin said.

"It was used until the end of steam locomotives working in Perth in 1971 but was retained purely as an advertising structure."