1813 Parish Canonically Established
1816 Land was purchased for $300, and the construction of the church began. The cost of the original building was $4,000.
1817 The first Mass in St. Mary's Church was celebrated on Sunday, December 14, 1817.
1819 Installation of the choir loft brought to completion the original plans of the church. The cemetery was established next to the church.
1828 C&O Canal construction brought many Irish immigrants to the area. The cemetery contains many unmarked graves of laborers who died while building the Canal.
1851 Many improvements and changes were made to the church. The old steeple at the back of the church surmounting the living quarters of the priest was demolished and a roof was erected over the former sacristy. The sanctuary today is located in the portion of the building formerly used as the sacristy and the present steeple was erected near the front of the church. The first rectory at St. Mary's was built, and consisted of a combined living room and dining room and kitchen on the first floor, with the priest quarters on the second floor.
1853 Improvement of the roads in the county led to the decision of the pastor to purchase a horse and buggy; this was the first transportation vehicle ever used by a priest in the county. Until this time, the priests had made their mission rounds by foot or on horseback.
1854 The first Stations of the Cross were installed in the church. These original stations hung on both sides of the church and they were colored pictures enclosed in glass with white wooden frames, and each measured twenty-two by sixteen inches. Each station name was printed in four languages, German, English, French and Italian.
1855 Sacrament of Confirmation was administered to forty-two boys and girls.
1857 The date of the earliest recorded First Communion class was Sunday, August 2, 1857.
1860 The first fund raiser, a Strawberry Festival, was held at the Fair Grounds.
1862 Civil War soldiers in uniform attended daily Mass.
1872 Land was purchased near the church for the founding of a school
1873 Extensive renovations to the church included the addition of a Sunday School room at the northwest corner of the church. The sacristy on the other rear corner of the church was enlarged and remodeled. A new altar was built and the stained glass window above the front entrance of the church was installed. Along the church side of the cemetery, a row of pine trees was planted, one of which remains today at the southwest corner of the church.
1882 During the celebration of Mass the church chimney caught fire and the flames quickly spread to an adjoining window frame. But the fire was quickly extinguished by parishioners.
1884 First recorded parish mission was held at St. Mary's.
1885 St. Mary's Church was painted and the large stained glass windows were installed; two rooms and a hall were added to the rectory and the cemetery grounds were improved. Land was purchased on Baltimore Road, about a mile from the church, for the new St. Mary's Cemetery.
1890 The sanctuary was made smaller and the altar rail, which formerly had run the entire width of the church, was reduced to the smaller area in front of the main altar where it is today. Additional pews were then installed at the front of the church and the present arrangement of two sections of pews was completed. The confessional was moved from the sacristy to the rear of the church and the choir loft was reduced in size. A wooden frame vestibule was added to the entrance.
1898 A stained glass window was installed above the main altar, and a new baptismal font was donated.
1901 First Midnight Mass was celebrated on Christmas eve.
1902 Installation of a gas plant to provide lighting was a welcome improvement over the old oil lamps.
1912 Installation of a steam heating system replaced the original coal stoves.
1929 A new altar with adoring angels on each side, and statues of the Blessed Virgin and of St. Joseph were contributed by the parishioners. New stations of the cross replaced those installed in 1854.
1930 An extensive renovation program was undertaken which included extending the choir loft to its present length, and installation of new pews and electric light fixtures. The turret grill work surmounting the facade on the exterior was removed, and the wooden vestibule was replaced with one of brick. The beams beneath the church were reinforced, and a steam heating system was installed to replace the hot air system.
1936 Three Masses were celebrated on Sunday: 7:00 a.m., 8:30 a.m., and 10:30 a.m.
1938 His Eminence Amleto Giovanni Cicognani, then Apostolic Delegate, formally blessed the new organ.
1951 St. Mary's Parish School was completed.
1975 F. Scott Fitzgerald and his wife Zelda were buried in the cemetery next to the Church.
1979 The Church was rededicated and renamed Chapel of our Lady. The original Church was named to the United States National Register of Historic Places.
1981 The roof was replaced and the steeple restored.
1982 The Chapel of Our Lady was completely refurbished. Interior walls were plastered and painted, and the floors were restored. The organ was cleaned and tuned.
1983 Our Lady of China Pastoral Mission began celebrating their Sunday liturgy in the Chapel.
1999 October - Memorial Mass of Dedication to honor Monsignor Kostick and dedication of the new altar.
2000 The Chapel of Our Lady was designated a Pilgrim Church of the Millennium for the Jubilee Year 2000 by James Cardinal Hickey, Archbishop of Washington.