The blast walls and barbed wire came down. The checkpoints went away.

Fifteen years after it was sealed off, the heavily fortified neighborhood in the heart of Baghdad was opened to the public on Monday.

The neighborhood, known as the Green Zone, had been cordoned off by the American military in 2003 to protect it from bombings during the war. The four-square-mile patch of land contained Saddam Hussein’s palaces, which later housed the headquarters of the American occupation authorities and military, and the Parliament building, the seat of the new Iraqi government.