1. Cinco de Mayo is celebrated in District Of Columbia as well as in Mexico. The holiday is celebrated on May 5th to commemorate the Mexican army's victory over the French at the Battle of Puebla in 1862. While not a major holiday in Mexico, it has become a popular celebration of Mexican culture in the United States.

2. In 1893, the World's Columbian Exposition was held in Chicago, Illinois. President Benjamin Harrison proclaimed May 5th as National Flag Day in honor of the 400th anniversary of Christopher Columbus' arrival in the Americas. District Of Columbia participated in this celebration by displaying the American flag across the city.

3. On May 5, 1925, the United Mine Workers of America led a strike of over 400,000 coal miners across the country in demand for better wages and working conditions. The strike lasted for nearly five months and ended with the workers receiving a 20% wage increase and improved safety measures.

4. The Washington Nationals played their first game at Nationals Park on May 5th, 2008. The team had previously played at RFK Stadium but moved to their new home in Southeast D.C. The stadium can seat up to 41,000 fans and has hosted numerous events over the years, including the 2018 NHL Stadium Series.

5. The National Building Museum in Washington D.C. officially opened on May 5th, 1985. The museum is dedicated to the history and architecture of buildings in the United States and features exhibits and events that explore the design and construction of all types of structures. In 1997, the museum began hosting the annual "Big Build" event which allows children to construct their own structures and learn about architecture and engineering.