This is the saddest and most neglected of all the tripoints I have visited (16 in total). The Belgium – France and Luxembourg wet tripoint is situated in industrial wasteland near Radange (LU), Athus (BE) and Mont-Saint Martin (FR). I have visited this tripoint twice, once in 2011 and once in 2018 as part of the IBRG BELEX trip. The 2018 trip showed some improvement but it stands in sharp contrast to the 2 other Luxembourg tripoints BEDELU and DEFRLU . In 2018 the confluence had been clearly widened with the Belgian bank reinforced with blocks.
The maps below indicate the tripoint location from the respective countries geo portals. The Luxembourg one is best for showing the tripoint location at the confluence of the La Chiers river (which is the border with Luxembourg and Belgium and France) and small unnamed stream (which is the border between Belgium and France).
A fellow border enthusiast Hugh Wallis visited this point in 2007 and recorded some interesting videos here. Details of the Luxembourg BM #1 restoration by other border enthusiasts is recorded here
BEFRLU 2011 Visit
The tripoint was very forlorn in 2011 with rubbish strewn access roads and the industrial area completely overgrown. It was not possible to see the tripoint confluence because of the overgrown foliage. I only spotted the Belgian bordermarker #1 as I walked away from the tripoint, it was not possible to from the river bank.