Britain's Queen Elizabeth II, who just celebrated 60 years on the throne, is rolling out the red carpet for them with receptions at International Olympic Committee meetings and a Buckingham Palace gala on Friday just before the opening ceremony.
Among those taking part are some former Olympians, like Prince Albert II (bobsled) and Princess Charlene (swimming) of Monaco and Britain's Princess Anne (equestrian). The princess' daughter, Zara Phillips, is part of UK equestrian team competing this year.
A lot of the royals took part in the flag-raisings for their countries at the Olympic Village. Since last weekend, several flag-raisings are held every day .
The International Olympic Committee is also holding a series of meetings in London this week to which the royals have been invited.