Postcards · 6 of 10
One postcard from my travels: dated when written, postmarked when sent.
Radioactive railway tiles
The vivid tiles at Berlin's Rosenthaler Platz U-Bahn station hide a surprising secret: due to being glazed with uranium oxide, they're radioactive! It's funny to think that thousands of commuters pass by every day without realising the tiles' uniqueness. Thankfully, the tiles pose no danger to the public.