The Water Forge is a monument of the old technology, the only one of its kind that has survived to this day. It is the largest and the longest operating hammer in Oliwa. It functioned for about 350 years using the power of the dammed waters of the Oliwa Stream.

The wooden building consists of two parts erected on both sides of the Oliwa Stream and a covered pier. There are three historic water wheels in the Forge. Two of them, 4 m in diameter, drive quarter-ton hammers, and the third, 3.1 m in diameter, drive the eccentric shears - the guillotine. The construction of the hammers comes from the second half of the 19th century or early 20th century.