原名斐蔚堂，1939年籌建。1951年3月，為紀念1925年“六三愛國壯舉”，改名為六三樓。

六三樓原名斐蔚堂，1939年籌建。六三樓是整齊對稱的兩層小樓。紅門、紅墻、紅窗格，紅色的不同層次勾勒出建筑的外部線條，從中也能看出一些現代簡約風格。中式大屋頂上豎立著兩根標志性的煙囪，對稱而立。二層設陽臺，憑欄處雕刻花紋。六三樓的突出特點就是對稱、簡潔，沒有多余的曲線。

The June Third Building, formerly called “Graves Hall”, went under way in 1939. The June Third Building is a small, neatly symmetrical two-storey building. The outside of the building is outlined with different tints of red colours—the red doors, red walls, and red panes, displaying a flavor of modern simplicity. Two iconic chimneys stand symmetrically on the large Chinese roof. On the first floor, there is a balcony with a railing in delicately carved patterns. The prominent features of the June Third Building are symmetry, simplicity, and the absence of redundant curves.

1951年3月，斐蔚堂改名為六三樓，以紀念1925年的“六三事件”。1925年5月30日，“五卅慘案”震驚中外。6月1日，圣約翰大學學生為悼念“五卅慘案”死難同胞，向校方提出罷課、宣誓、聚集向國旗行禮和唱國歌等要求。圣約翰美籍校方不準罷課，并宣布放假7天。中國教員和學生開會議決在校內升半旗，向被害同胞致哀。3日早晨，師生們在羅氏圖書館前旗桿處升半旗后，到大會堂集會，會畢又返旗桿處，但國旗已被校方撤去。滿腔愛國義憤的學生聚集大禮堂，向國旗行三鞠躬禮。

In March, 1951, the Graves Hall was renamed “the June Third Building” in memory of “the June Third Event” in 1925. On May 30, 1925, the “May 30th Massacre” shocked China and the world. On June 1, to mourn the compatriots who had died in this event, the students of St. John’s University demanded from the authorities of the university the permission to strike, to take oaths, to gather to salute the national flag, to sing the national anthem, etc, and were rejected; instead, the university announced a seven-day holiday. The Chinese teachers and students held a meeting and decided to raise the flag at half-mast in the university to pay tribute to the victimized compatriots. In the morning of June 3, the teachers and students raised the flag at half-mast in front of the Low Library and gathered in the main hall. They returned to the flagpole after the meeting, only to find that the national flag had been removed by school officials. Out of patriotism and indignation, the students gathered in the auditorium and bowed three times to the national flag.