The Opening Ceremonies got the Summer Olympics off to a record-setting ratings start for NBC.

Friday night’s four-hour festivities from London drew an average audience of 40.7 million viewers, according to Nielsen, making it the most-watched kickoff to the Summer Games on record. The tune-in was nearly 6 million larger than for Beijing in 2008 and bested the previous high, set by the Atlanta Games in 1996 (39.8 million), by nearly 1 million.

In household rating/share, Friday’s opener averaged a big 21.0/37, the best for a non-U.S. Summer Olympics ever, and the second best for a non-U.S. Games (summer of winter) in 36 years — since Innsbruck in February 1976 (23.2/37 on ABC).

While population gains account for some of the record-setting total-viewer count, the household rating for Friday night — with more than one-fifth of the nation’s TV homes watching — is particularly impressive considering how many more viewing options than there were in previous decades.

The 21.0 household rating is the highest for any network on a Friday night since the Opening Ceremony of the Salt Lake City Games in February 2002 (25.2).

The top local-market scores Friday night were a 27.8 household rating/49 share in San Diego and a 26.8/48 for both Washington, D.C. and West Palm Beach. Highest-rated among the top 10 markets was Boston (24.8/45), followed by two cities that have hosted the Summer Games over the last 30 years: Los Angeles (24.2/44) and Atlanta (24.1/39).

Preliminary affiliate-based numbers show the Olympics coverage on NBC averaging about 42 million viewers from 8 to 11 p.m., more than five times the combined primetime audience of ABC, CBS and Fox (8 million).

The start of the London Games was a huge draw as expected in England, where it aired live starting at 9 p.m. local time. The BBC reported an average audience of 22.4 million viewers for an 82.5% audience share.

Film director Danny Boyle, who orchestrated the Opening Ceremony, flavored the event with plenty of British touches, including songs from many great U.K. artists such as the Who and the Rolling Stones.

NBC and its cable brethren will now begin televising the competition from these Games, with more than 5,000 hours of coverage set to overtake the airwaves. The Olympics will end Aug. 12.