The legend of secret tunel under Danube
There are numerous theories about the existence of this tunnel, but there is no confirmation in historical sources that such a thing exists under the Danube bed. There is no drawn tunnel on the maps, there is no sign that there was an attempt to build it, but the proponents of these theories claim that this does not have to mean anything because before the Austro-Hungarians there were Turks, Romans, and Celts here, who could have been the builders of such tunnels.
Legend has it that you could enter a secret tunnel under the Danube behind the altar of the church of St. George in Petrovaradin, and use it to reach the church of St. Ivan Nepomuk on Mostobran (Bridgehead) - Brukšanac (Novi Sad side this church not exist any more). On the Danube Quay, under the Monument to the Raid Victims, along the shore itself, there is still a visible remnant of the Bridgehead - a small tower (a round stone pillar with a rounded top). This stone pillar, built in 1831, was used to measure the water level at the pier. It is the only remnant of the former Bridgehead, which was an integral part of the Petrovaradin fortress from 1694. It was a fortification with ramparts and gates facing the city, and a flat base facing the Danube. It served to protect the bridge, and partially the fortress.
An Austro-Hungarian officer allegedly passed through the tunnel under the Danube last in 1913, and carried his lover from one side to the other in his arms. At the same time, the tunnel began to collapse, and the couple barely made it out alive. The last Austrian emperor Charles I and his wife Zita allegedly passed through the tunnel. Some natives in their later years of life swore that this tunnel existed, but in their stories, reality and legend are usually intertwined.

It is believed that at the end of the First World War, the last Austro-Hungarian general was ordered to wall up all entrances and exits of the tunnel, before the Serbian army entered the building.

Some enthusiasts claimed three years ago that there is a straight line structure under the Danube bottom between 8 and 9 meters. They state that Based on the sonar research of the Danube, a 3D model of the tunnel is currently being developed, which could be a key piece of evidence.
How to find log chache on final location
1. Go to Bridgehead and when you go down the stairs to the Danube, how many metal moldings are on the stairs (last part from the brick pillar to the bottom)? It is A.

2. Go to the the church of St. George in Petrovaradin, on the front wall of churche, there is a sculpture of a man with a cross on his back. What year is indicated in the picture below, (biger number in right corner? It is B

Final location
It is near St. Georg church
X=A - 3
Y=B - 1172
N 45° 15.24X ' E 19° 51.Y'