This is actually an Orthodox church, the first that I've ever visited. St. Andreas is the patron saint of Patras, hence the name. Photography isn't allowed inside, but from the outside nobody bothered me. The inside is worth a visit, though, as it's colourful, and quite ornate. Nothing like any church I've been to before, other than, of course, the high vaulted ceilings and great attention to detail. According to...

www.infocenterpatras.gr/mnimeia/mnimeia_eng.htm

This is the largest Orthodox church in the Balkans (although many people object to the notion that Greece is a Balkan country), and can accomodate 5,500 worshippers and guests. Supposedly among the relics are is St. Andreas's skull and finger, stored in a large silver case. In addition, the site is a pre-Christian religious site, as prior to the construction of the church, a pagan temple to Demeter stood here, although a number of churches have stood here in the interim. The current church only dates to 1908.