Bacchanal is Columbia's annual 'party week', when we pretend we're actually a state school. It conveniently occurs at the end of spring semester when the weather is nice, but papers are due. This means that not only will you be more likely to be locked inside Butler Library than outside participating, but the noise will penetrate the library and drive you crazy the whole time. Bacchanal culminates with the Concert on the Steps.
It is widely believed that Baccahanal is a poor copy of other universities' "Spring Fling" festivities. At the very least, the classical name is in keeping with the Core Curriculum and campus architecture.
Also, it used to be heavily alcohol-oriented, until the administration cracked down.
It is organized by Bacchanal Events.