Crystal Palace is full of leftfield historical delights, hangovers from its time as the home of the Great Exhibition in its late Victorian heyday. These include its famous, lovably wonky dinosaur sculptures and disintegrating stone balustradres and steps that once led up to a gorgeous glass palace (which sadly burnt down in 1936).
Still, few casual Sunday strollers are aware that there's even more wonderful stuff going on underground. This hidden gem of Crystal Palace, a Grade II-listed Victorian subway, was originally built to connect the neo-gothic railway station to the once grand Crystal Palace back in 1865. While not currently open to the public, look out for rare open days when you can have a look at its eye-popping diamond-shaped designs, picked out in different colours of brick, and graceful vaulted ceilings. But be warned: whenever this place is open for visitors expect long, long queues.