The Queen's Chapel in central London is an adjunct to the magnificent St. James's Palace in Pall Mall. It was added to the palace under instruction from its designer Inigio Jones and built somewhere between 1623 and 1625. Its use then, and today, is as part of the reigning monarchs personal religious establishment, the Chapel Royal. Visitors should be aware not to confuse the establishment, the Chapel royal, with the room in St. James's Palace across the road called the Chapel Royal!
The specifics of its use by various monarchs throughout its existence has varied from ruler to ruler, at the time of its construction it was used as a Roman Catholic chapel, and was the main place of worship used by Charles I's queen, Henrietta Maria, as she was herself a Catholic.
From the 1690's the place would have mainly been used by visiting continental Protestant Courtiers, the chapel having no permanent use as a place of worship for any current British Royal.
In modern days, the Queen's Chapel was the place where, during the preparations for the Queen's Mothers “lying-in-state” in Westminster Hall, her body was kept for several days.