Banqueting House on Whitehall is the last surviving part of the Palace of Whitehall and one of London’s most important Stuart-era landmarks. It’s especially known for Inigo Jones’s classical design and the Rubens ceiling in the main hall.
 
It became famous as the site linked to the execution of Charles I in 1649, outside the building. After a fire in 1698, it was repurposed and later survived as a historic building rather than a working palace space.
Its architecture is really important in the development of the English Neo-classical style
 
Interesting facts..
The undercroft beneath the hall was designed as a private drinking space for James I and his closest companions, and it survives today in a much plainer form than it originally had.
The building was used for ceremonies such as Royal Maundy and the “touching” ritual, where monarchs were believed to heal disease by touch. Yes that as really a thing!