The corridor below Běhounská Street was discovered in 1999. A shaft made in the pavement near the Augustinian monastery on Moravské náměstí (Moravian Square) uncovered a half-buried corridor that turned out to be almost 80 metres long after it was emptied. The western end of the corridor is near the entrance to Kino Scala (Scala Cinema); the entrance end is in an inclined wall under the passage from Běhounská Street into the park. But this finding was not the last. After punching through the sloping wall, a 90-metre passageway was discovered leading under the park to Janáček Theatre.

To find out why these structures were built, we must go back to the 18th century, when the prior of the Augustinian monastery conducted lengthy negotiations with the military fortification commission and the city administration to fill the moat between the monastery and the city. They wanted to build the southern wing of the monastery above it. In 1731, the filling of the moat was finally permitted, on the condition that the monastery would ensure that the municipal canal and water main that led under the town moat were not damaged by the planned construction.      

A protective tunnel was built above the sewer running through the moat, which was then buried. The tunnel lying under the park is probably a folded branch of the Kartouzský watercourse, which was used to bring water from Královo pole to the Mercury Fountain on náměstí Svobody (Freedom Square). Both were therefore built simultaneously in 1731. The protective corridor, 2.4 metres in height and width, was built very simply with exceptionally precise craftsmanship. The vertical walls supporting the brick vault are made of pink stones from the Brno igneous rock and supplemented with brick fragments with a detailed filigree, reminiscent of a mosaic. Even the water gallery was made very well. It is 1 metre wide, with a height varying from 1.2 to 2 metres, and it runs 6 metres below ground level. It descends from the city and ends at the Rooseveltova Street tram tracks.