Prince Albert II and Princess Charlene of Monaco are expecting twins later this year
The first sovereign to take the name Louis was only the second man to be called Prince of Monaco. Louis I was born in the Prince's Palace in the country in 1642, the eldest son of Ercole Grimaldi and his wife, Maria Aurelia who was a member of the powerful Genoese clan, the Spinolas. Ercole became known as Hercule and was heir to the first man to rule Monaco as a prince, Honore II, but he died before his father and so Louis got the title in 1662. He ruled the principality until 1701 and was succeeded by his son, Antonio.
Louis II, Prince of Monaco, who ruled between 1662 and 1701
The second Louis of Monaco would begin his reign over 200 years later. Louis Honore Charles Antoine was sovereign between 1922 and 1949 but packed plenty into his life before that. He was born on July 12th 1870, the only child of the then heir to the throne, Albert I, and his wife, Lady Mary Victoria Hamilton. Louis' parents parted soon after his birth and he was raised in Germany by his mother and step-father before returning to Monaco to learn the art of monarchy. But he ended up joining the French Foreign Legion while his father became a well known sovereign prince with a love of culture and, in particular, oceanography.
Louis II, Prince of Monaco who ruled the state from 1922 until 1949
This second Louis took the throne on his father's death and his great passion in his reign was sport with Monaco Football Club taking shape soon after his accession and the first Grand Prix to be held in the principality taking place in 1929. Louis had had a relationship with a singer called Marie Juliette Louvet which produced a daughter, Charlotte, who in 1919 was declared heir after a change to the law. She passed her rights to her son, Rainier, who succeeded on Louis' death in 1949.
Rainier Louis Henri Maxence Bertrand was the sovereign Prince of Monaco between 1949 and 2005
Louis was also one of Prince Rainier III's names and the current sovereign is called Albert Alexandre Louis Pierre. It is a name with plenty of history in Monaco and the one chosen in the recent poll as the most likely to feature in a birth announcement from the Prince's Palace later this year should one of the royal twins be a boy.