「牧師樓」建於1909年，原為加拿大宣教士吳威廉牧師宿舍。由於1923年吳牧師病逝後，明有德、孫雅各兩位牧師在台北神學校與淡江中學服務時，也 先後寓居於此，故有「牧師樓」之名。 二次大戰期間，牧師樓一度為淡江中學男生宿舍，並改名為「青龍寮」。戰後，除了蘇若蘭和苗爾甘牧師曾入住外，也曾作為純德女中之琴房教室。最後一位居住在 牧師樓的宣教士為郭德士長老，後於1965年因真理大學創校所需而搬離。 牧師樓為吳威廉牧師設計之殖民地式紅磚迴廊建築。比例精準，砌功精湛，是淡水難得之古蹟。
The House of Reverends (Bok-Su Lao) Bok-Su Lao was originally built for the Reverend William Gauld’s as his residence in 1909. After his passing in 1923, the house became the residence of the Reverend Hugh MacMillan, who served at Taipei Theological School, then the Reverend James I. Dickson at Tamkang High School. Because the house was home to these pastors, it was called Bok-Su Lao. During W.W. II, the house became the boy’s dormitory of Tamkang High School and was renamed Chhin Liông Liaû, “Hall of Azure Dragon.” After the War, the house became the residence of the Reverend James Sutherland and then the Reverend George Malcolm. At one point it housed a piano studio of Chun-Teh Girls' High School. The last occupant of the house Elder John Geddes who vacated the premises in 1965, After this it became an administration building for Tamsui Oxford College (now Aletheia University) founded the same year. One part of the house would be converted into a faculty restaurant and the building was nicknamed “The Red House.” Built and designed by the Reverend Gauld, the building’s fine pointed masonry and redbrick porch have made this rare colonial-style architecture a work of art among the historical treasures of Tamsui.