The hourse guards.

In London, the term "horse guards" typically refers to the ceremonial mounted soldiers who guard the official royal residences and perform ceremonial duties. The two most famous units associated with horse guards in London are the Household Cavalry and the Queen's Life Guard.

These horse guards not only have ceremonial roles but also perform important ceremonial and state duties, including escorting members of the royal family and other dignitaries, participating in state processions, and providing a visible symbol of the British monarchy.

It's worth noting that the term "horse guards" can also refer to the Horse Guards building itself, which is a historic military building that houses administrative offices and serves as the entrance to St James's Park. The building has a long history and is a significant landmark in central London.

Seeing the horse guards and witnessing their ceremonial duties is a popular activity for visitors to London, offering a glimpse into the rich tradition and pageantry of the British monarchy.