Where: Mansion House
The official residence of the Lord Mayor of London is a grand, Palladian-style building completed in 1758 which has changed very little over the centuries.
Guided tours (currently paused due to COVID-19) usually take place every Tuesday, and let you take in the ballroom, elegant drawing rooms and the curiously-named Egyptian Hall which has more in common with the Roman era.
Until it reopens there's plenty to admire from outside, including a dramatic temple portico at the front entrance, flanked by impressive columns.