In 1874, a national festival was held at Þingvellir to celebrate 1000 years of the settlement in Iceland. On this occasion, King Kristian IX presented Icelanders with their first constitution, according to which the Alþing was granted limited legislative and financial powers. Many Icelanders went to Þingvellir to witness an event that marked a watershed in their campaign for independence.
In the summer of 1930, a large festival was held at Þingvellir to celebrate the Millennium of the Alþing itself. The Alþing festival was the first general celebration of Icelanders where a substantial proportion of the nation was present, about 30-40,000 people.
The foundation of the Icelandic republic took place at Þingvellir on the 17th of June 1944, the birthday of one of its national heroes, Jón Sigurðsson. Despite rain and wind for most of the day, the huge number of visitors gathered were not troubled, for this was the most important day in the history of Iceland. Election for presidency took place at Lögberg, and state leader Sveinn Björnsson became the country's first president. At the end of the programme at Lögberg, the first cabinet meeting of the Republic took place, at which the President confirmed the law on the national flag and coat of arms.
A new period in the history of the country had begun. In 1974, Icelanders celebrated the 1100th anniversary of the settlement. The sun shone on the numerous guests who took part in the first festival televised directly to the people. On 17th June 1994, a celebration was held at Þingvellir to mark 50 years since the foundation of the Icelandic republic. Tens of thousands of Icelanders celebrated this event, along with the many foreign guests who were invited.
In 1999, a festival to celebrate the Millennium of Christianity was set in motion.
This included a series of events all over the country. The celebrations culminated in a two-day festival at Þingvellir in early June 2000, with thousands of Icelanders participating in various programmes and religious ceremonies.