Ok this 14th-century market is absolutely gorgeous and somehow barely any tourists know about it. Hidden at Gracechurch Street in the financial district which totally explains the tourist absence — Office workers grab lunch here but zero tour groups swarm it like other historic spots.

Harry Potter filmed Diagon Alley entrance scenes here (specifically the blue door of Leadenhall Market leading to the Leaky Cauldron) but unlike Platform 9¾ or other filming locations, no crowds recreating movie scenes. The ornate Victorian ironwork roof restoration from 1881 creates incredible natural lighting through cobblestone streets. Feels like stepping into atmospheric 1880s London.

Lamb Tavern inside dates from 1780 serving traditional pub atmosphere with Fuller's ales £5.50-7. Several decent lunch spots including Champagne + Fromage for cheese plates £8-12. Obviously completely free to wander and photograph the incredible architecture.

Bank or Monument tube stations (Central, District, Circle, Northern lines) both 2-minute walks. Perfect quick detour when doing City of London walks or Tower of London visits — Adds maybe 15 minutes but delivers serious wow factor most guidebooks somehow miss.