原名斐蔚堂，1939年筹建。1951年3月，为纪念1925年“六三爱国壮举”，改名为六三楼。
六三楼原名斐蔚堂，1939年筹建。六三楼是整齐对称的两层小楼。红门、红墙、红窗格，红色的不同层次勾勒出建筑的外部线条，从中也能看出一些现代简约风格。中式大屋顶上竖立着两根标志性的烟囱，对称而立。二层设阳台，凭栏处雕刻花纹。六三楼的突出特点就是对称、简洁，没有多余的曲线。
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，斐蔚堂改名为六三楼，以纪念1925年的“六三事件”。1925年5月30日，“五卅惨案”震惊中外。6月1日，圣约翰大学学生为悼念“五卅惨案”死难同胞，向校方提出罢课、宣誓、聚集向国旗行礼和唱国歌等要求。圣约翰美籍校方不准罢课，并宣布放假7天。中国教员和学生开会议决在校内升半旗，向被害同胞致哀。3日早晨，师生们在罗氏图书馆前旗杆处升半旗后，到大会堂集会，会毕又返旗杆处，但国旗已被校方撤去。满腔爱国义愤的学生聚集大礼堂，向国旗行三鞠躬礼。
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.
