A roving UHub correspondent decided discretion was the better part of driving valor and turned around when he saw how flooded St. Thomas More Road, between the BC lower campus and the Chestnut Hill Reservoir, was after today's torrent.
The reason it's called the lower campus is because it's down from the Heights for which BC is better known. In fact, until 1949, most of it was underwater, part of a second reservoir, known as the Lawrence Basin, just across the street from what we know call the Chestnut Hill Reservoir, as seen here in this 1893 photo by the Metropolitan Water Board (note the large pumping station at the top, preserved today as the Waterworks Museum, as well as the smaller pump house off to the right, which still stands, although no longer in use, since the Brookline reservoir to which it once diverted water from Lake Cochituate is no longer in use, either):
In 1948, the state declared the Lawrence Basin "inactive" because of construction of the far larger Wachusett and Quabbin reservoirs, and sold the basin and adjoining land to Boston College, which filled it in and put a football stadium and dorms on the newly dry land.
Meanwhile, Ari Ofsevit reports part of Charles Street became a lake - with an ad hoc stream feeding the Public Garden Lagoon, which came close to overflowing its banks. Like St. Thomas More Road, Charles Street was once underwater as well, as part of the Back Bay, back when it was actually a bay, and the original inhabitants would build fish weirs there.