I always wondered what the extension on the Višegrad bridge – the Mehmed Paša Sokolović bridge – was for, now I know

"In the middle of this bridge stood a wooden tower, the time of its creation is unknown, and it was demolished in 1886. The tower was a guardhouse with a passage below it, which was closed by strong oak doors on both sides. There were several small cannons called shibe on the tower. On the bridge there were two verses in verse with engraved years – on the first 971-/1571, and on the second 985/1577." More about the bridge and pictures at the link https://www.biserje.ba/rijetka-fotografija-visegradskog-mosta/