On April 4

A building collapsed on tribal land in Thane in Maharashtra, India, causing 74 deaths.

Georgian Airways Flight 834 crashed at N'djili Airport in Kinshasa, killing 32 people and leaving one survivor.

The current flag of Hong Kong (pictured) was adopted for post-colonial use during the Third Session of the Seventh National People's Congress.

Evan Mecham, Governor of Arizona, was removed from office after being convicted in his impeachment trial.

Vietnam War: On a mission to evacuate children from South Vietnam, a U.S. Air Force plane crash-landed at Tan Son Nhut Air Base, killing 78 children and 60 others.

Bill Gates and Paul Allen founded Microsoft in Albuquerque, New Mexico, to develop and sell BASIC interpreters for the Altair 8800.

A C-141, dubbed the Hanoi Taxi, flew the last mission of Operation Homecoming to return American prisoners of war from Vietnam.

A year after the completion of the second of the complex's twin towers, the World Trade Center in New York City was officially dedicated.

American civil rights leader Martin Luther King Jr. (pictured) was assassinated in Memphis, Tennessee.

Twelve nations signed the North Atlantic Treaty, establishing NATO, an international military alliance whereby its member states agree to mutual defense in response to an attack by any external party.

An earthquake hit the Kangra Valley in India, killing at least 20,000 people and destroying 100,000 buildings.

The Kennel Club, the world's oldest kennel club, was founded in the United Kingdom after Sewallis Shirley became frustrated by trying to organise dog shows without a consistent set of rules.

Bryant's Minstrels premiered the minstrel song "Dixie" in New York City as part of their blackface show.

William Henry Harrison became the first U.S. president to die in office, sparking a brief constitutional crisis regarding questions of presidential succession that were unanswered by the U.S. Constitution.

Napoleon abdicated as Emperor of the French and named his son Napoleon II to replace him.

Queen Elizabeth I knighted Francis Drake for completing a circumnavigation of the world.

The Byzantine Empire and the Republic of Venice signed a five-year peace treaty.

The Komnenos dynasty came to full power with the coronation of Alexios I Komnenos (pictured) as Byzantine emperor.