Buckingham Palace is the official residence of the monarch and has been since 1837.
Whilst you do have to pay to visit the state rooms you can stand by the Queen Victoria Memorial to view the magnificent building. You can watch the guard mounting ceremony at 11.30 everyday throughout the summer.
UG: St James's Park 0.57km
UG: Green Park 0.59km
UG: Victoria 0.65km
Public access to the area in front of the palace by the Victoria memorial is always open.
Always check details regarding opening hours, accessibility and pricing before travelling.