The "Gates of Paradise" situated in the Baptistery are a copy of the originals, substituted in 1990 to preserve the panels after over five hundred years of exposure and damage. To protect the original panels for the future, the panels are being restored and kept in a dry environment in the Museo dell'Opera del Duomo, the museum of the Duomo's art and sculpture. Some of the original panels are on view in the museum; the remaining original panels are being restored and cleaned using lasers in lieu of potentially damaging chemical baths. Three original panels made a US tour in 2007-2008, and then were reunited in a frame and hermetically sealed with the intention of making the panels appear in the context of the doors for public viewing. One of the few copies made in the 1940s is installed in Grace Cathedral, in San Francisco; copies of the doors are also crafted for the Kazan Cathedral in Saint Petersburg, Russia, and in 2017 for the Nelson-Atkins Museum of Art in Kansas City, Missouri.