After he is installed as the archbishop of Washington on May 21 at the Basilica of the National Shrine of the Immaculate Conception, Archbishop Wilton Gregory will automatically become the chairman of the board of trustees of the basilica, one of the most recognizable sites in Washington, D.C.

Each year, about one million pilgrims make their way to Fourth Street and Michigan Avenue, N.E. to pray at what in what is often referred to as “Mary’s House.” Those pilgrims have included St. John Paul II, St. Teresa of Calcutta, Pope Benedict XVI, Pope Francis, Lech Walesa and the Dalai Lama.

The basilica – the largest Catholic Church in North America and one of the 10 largest in the world – is not a parish church. Technically situated within the parish boundaries of St. Anthony Church, which is located at 12th and Monroe Streets, N.E., the basilica is a place where Masses are offered and Confessions are heard, but it is not a place for weddings or funerals, although rare exceptions to that rule have been made: President Lyndon Johnson’s daughter, Lucy, was married there and a funeral Mass was celebrated there for Father Gilbert V. Hartke, founder of CUA’s drama department.

The Solemnity of the Immaculate Conception of the Most Blessed Virgin Mary, to which the National Shrine is dedicated, is the patronal feast day of the United States.

Plans for the National Shrine date back to the early 20th century.

On May 13, 1846, the 22 U.S. Catholic bishops, representing the then 28 states and meeting in Baltimore, placed the United States under the patronage of Mary’s Immaculate Conception. About 60 years later, then-Father (later Bishop) Thomas J. Shahan, a professor at the Catholic University of America, espoused the cause of a national shrine dedicated to Our Lady. When he became fourth rector of the university in 1909, he proposed building the shrine on CUA’s campus.

The National Shrine’s foundation stone was laid in 1920.

The Crypt Church was completed in 1926, and between 1930 and 1932, the crypt area was extended to include the Lourdes Chapel, a lobby, Memorial Hall, and the Founder’s Chapel (where Bishop Shahan is buried).

The Great Depression, World War II and a lack of funds delayed further construction of the shrine until the U.S. bishops decided to mark the 1954 Marian Year by pledging themselves to building the basilica’s Great Upper Church. Catholics in every U.S. parish responded to a national appeal and construction of the shrine resumed.

In the 1950s, an iconography committee established an “icon scheme” for the shrine and its seven domes.

In 1957, the Knights of Columbus donated $1 million for the shrine’s bell tower, which is 329 feet high and supports 56 bells ranging in weight from 21 to 7,200 pounds. The tower is the second highest structure in Washington, surpassed only by the Washington Monument.

The National Shrine was dedicated in 1959, with its only interior decoration then being the monumental Christ in Majesty mosaic behind the main altar.

Four of the domes – The Descent of the Holy Spirit, The Glorification of the Lamb, The Last Judgment and The Creation – were completed between 1966 and 1970. Work was completed on the fifth and sixth domes – the Redemption Dome and the Knights of Columbus Incarnation Dome – in the last decade. With the dedication of the Trinity Dome Mosaic in December, 2017 the National Shrine has been completed according to its original architectural and iconographic plans.

Since its dedication, chapels and oratories have been constructed by the faithful of various ethnic backgrounds and dedicated to Mary under numerous titles. Chapels have been donated by Irish, French, Mexican, Lithuanian, African-American, Lebanese, Filipino, Polish, Italian, Asian-Indian, Austrian and many other groups of Catholics.

In 1990, Pope John Paul II issued a decree elevating the shrine to the rank of a basilica.

The interior of the Great Upper Church is 399-feet long and can accommodate more than 6,000 worshipers. The Crypt Church on the lower level is 200-feet long and 160-feet wide and can seat more than 400 persons. More than 2,000 tons – 4 million pounds – of marble was used for the interior of the shrine.

The Basilica of the National Shrine of the Immaculate Conception is located at 400 Michigan Ave., N.E., with ample free parking. It is easily accessible by Metro, just a short walk from the Red Line’s Brookland Station.