Plaques on the ground in Budapest and marking the line of fortresses, camps and stations of the Roman army along the Danube (Pannonian Limes)
The current plaque shows Lugio, the Roman name of the fort in Dunaszekcső, Hungary
In the next picture that contains the current picture, you can see the lines of the Danube river to the right of the board Click for a larger image
In the next photo taken on the same day, part of the line of fortresses was seen, with the route of the Danube River between the various plates Click for a larger image