The United Kingdom's 1902 State Landau is a horse-drawn carriage with a flexible leather roof which drops in two exact halves, back and front.
Front
Back
The Duke and Duchess of Cambridge after their wedding in 2011
The Queen and the Duke and Duchess of Cornwall at her Diamond Jubilee celebrations 2012
In coachbuilding, a landau is a four-wheeled carriage with a roof that can be let down. It was a luxury carriage. The low shell of the landau provides maximal visibility of the occupants and their clothing, a feature that makes a landau still a popular choice for Lord Mayors in the United Kingdom on ceremonial occasions.
1816 landau, wind-up side windows and forerunner to the true convertible car
1849 daguerreotype of a landau carriage ready for a family outing.
In Vienna, landaus are called fiacres because they can be rented.
A five-glass landau carriage in Geraz do Lima Carriage museum