Wander around the hotel lobby where a glass floor reveals excavations of the old medieval town; take a seat in an amphitheatre where animal dissections once took place; let yourself be moved by the sounds of the largest pipe organ, still used today to bring silent films to life; take a break in one of the few well-preserved Baroque vaults housing coffins fitted with windows; climb onto a bunker that contained anti-aircraft guns during the Second World War and accept a Russian soldier's invitation to admire it from within; take a dip in one of the most beautiful bathing spots built during Europe's Art Nouveau movement; enjoy a stroll under the Spree river; go see the very first computer (designed by a Berliner) or the first synthesizer of East Germany; scale the mountain of rubble where a Skiing World Cup race was held; station yourself at the peak of the artificial hill where aviation pioneer Otto Lilienthal made his first attempts at flight; and grab a bite on the island in the Havel river where Werner von Braun launched his first rocket. Absent from the usual "must-see" lists despite residing in the heart of the bustling capital, fascinating historical treasures can be found all over Berlin's city centre and its large surrounding neighbourhoods. Take another look and discover the hidden gems eluding those who think they know Berlin inside out.