Thunderous explosions and dense black smoke swirled through the center of Baghdad on Monday when at least one car bomb blew up in an underground parking garage, setting off dozens of secondary explosions and killing at least 59 people, police said. A second bombing nearby killed at least nine. The blasts shattered the city center on the first anniversary, according to the Muslim lunar calendar, of the bombing last year of the important Shiite Golden Dome shrine in Samarra, north of the capital. That attack by al-Qaida in Iraq militants set off the torrent of sectarian bloodletting that has turned Baghdad and much of central Iraq into a battleground. A column of smoke hundreds of feet wide billowed a thousand feet into the air above the market near the east bank of the Tigris River and near the Central Bank building. Ambulances and pickup trucks rushed many of the 150 wounded to nearby al-Kindi hospital in the largely Shi'ite region that has been hit be a series of deadly bombings since the first of the year.