Queen Elizabeth II's Platinum Jubilee, in photos

Four days of celebrations honoring Queen Elizabeth II’s 70 years on the throne have kicked off with formal Platinum Jubilee celebrations.

First came the Trooping the Color ceremony with horses. Then the queen joined members of her family Thursday on the balcony of Buckingham Palace as 70 planes flew overhead.

The 96-year-old Elizabeth is Britain’s longest-reigning monarch and the first to serve for seven decades. During a four-day holiday weekend, thousands of street parties are planned around the country.