The Lloyd's building in the City is London's most striking piece of high-tech architecture — Exposed steel and glass with services on the exterior. The ground floor lobby is accessible during business hours and you can witness the famous escalator atrium.

Security asks what you're visiting for — Simply mention architectural interest. They're accustomed to enthusiasts. The building is most spectacular viewed from outside at night when illuminated. 1 Lime Street, nearest stations Bank or Monument. Open weekdays 9am-5pm.