There are at least three bands called Circa:

1.
Along with the march of December 2005 came in the band CIRCA. A sketch of desire to create a music circling around heavy rock riffs but with a melodic approach and to finally play their hearts out, pushed Rey Olarte (drummer) and Sam Salantes (guitars) to set-off a new band. They were formerly known as milk and money and the new band name followed after a couple of choices from a list of names. They chose a name that is short and easy to remember; Simple yet catchy. Thus the birth of CIRCA.

Stepping a bit further is the addition of JC Ascuncion to fill in the second guitar. Held sessions and played their original compositions which has been written before the band started. Finally they have to look for a vocalist to provide life to their melodies for their lyrics. A month of painstaking auditions and practices CIRCA finally chose JB Liwanag for vocals. The quartet was formed to bring into harmony their captivating originals, experimental sounds, and intense feelings, while incorporating different music influences (Paramore, Urbandub, Saosin, Up dharma down, Anberlin, Last Winter, Bullet for my Valentine, Foo Fighters etc.) but with a mark of individuality creating their own niche in their genre of music.

2.
Circa, or better precisely "Circa:" is new band founded by memebers of legendary progressive rock band Yes from various time periods - Billy Sherwood (bass, vocals), Tony Kaye (keyboards, Hammond organ), Alan White (drums) and Jimmy Haun on guitars (btw. Haun was one of the main guitarists on the album Union). On 30 July 2007, the band released their debut album, CIRCA: 2007. The album includes two tracks based on material Billy Sherwood co-wrote with Trevor Rabin in 1995 and guest appearances by Michael Sherwood and Cole Coleman.

3.
Another alias of Jason Leach