In 2002, a survey of the underground around the Slavie Hotel on Solniční Street yielded a very interesting find. A probe carried out directly in front of the restaurant's summer garden revealed an underground structure of a medieval half-cylindrical bastion at a depth of two metres under the pavement.

This discovery was initially no different from the others. The inner space with a bedded backfill with remnants of rotten wood appeared to be a larger cellar. However, after clearing out part of the cave-in, it became apparent that it was a much more valuable item.

The stone wall, built in a rounded shape, suggested that further surprises would not be long in coming. After some subsequent excavation, medieval loopholes were uncovered in the unfilled part of the cellar - niches fitted with keyhole bullets. At that point it was clear that a former fortified bastion had been discovered, at the height from which our ancestors defended their city. It was called the "Weise Pulwer Thurm", the White Dust Tower. It was one of the few towers that were demolished only in the last phase of the destruction of the walls and formed the corner of the northern and western lines of the medieval fortress belt. As its name suggests, it served not only its strategic function but also as a powder magazine. The use of the towers for the storage of this dangerous but strategically important material was a common practice and a logical security measure.

Accidental explosions were no exception at a time when there were no lightning rods and buildings were lit with open flames. An example is the explosion of seventy barrels of gunpowder stored in the tower of the Merry Gate. The explosion, which occurred in 1580 and damaged many of the surrounding houses and literally tore the gate tower apart, was caused by a lightning strike.