In 1939, St. Matthew's was designated a Cathedral following the creation of the combined Archdiocese of Baltimore and Washington. Later, it became the Mother Church of the new archdiocese of Washington when it was established as its own, separate entity in an announcement made by Pope Pius XII.
This cathedral is dedicated to the Apostle Matthew, the patron saint of civil servants. Architecturally, the structure is of the Romanesque Revival style, with Byzantine-inspired elements. It is constructed of red brick and sandstone, and features a terracotta trim. The shape of the church is that of a Latin cross measuring 155 feet × 136 feet. An octagonal dome caps the cathedral which, with the cupola and crucifix, reaches a total height of 200 feet. The interior of the church is decorated with marble and semiprecious stones, as well as an impressive, 35-foot mosaic of its patron saint, created by Edwin Blashfield. Additionally, the structure includes an 8-tomb crypt near the entry of the St. Francis Chapel, wherein former archbishops are interred.
This cathedral is notable as the location for several historic funeral Masses, conducted for such notable individuals as television anchorman Frank Reynolds (1983), U.S. Supreme Court Associate Justice William J. Brennan, Jr. (1997), and Chief Justice William Rehnquist (2005). In 1963, a Pontifical Requiem Low Mass for President John F. Kennedy was recited at this location during his state funeral service. The spot where Kennedy's casket was place is marked inside the church.
The cathedral has also served as the site of other important Masses. For example, Pope John Paul II celebrated Mass at St. Matthew's during a 1979 visit to D.C. One of the most famous Red Masses in the world is hosted at this Cathedral annually, with the Justices of the Supreme Court, members of Congress and the Cabinet, and dignitaries (sometimes including the President of the United States) in attendance. The Cathedral of St. Matthew the Apostle was added to the National Register of Historic Places in 1974.