The U.S. Capitol dome is seen last month before recent work began. (Chip Somodevilla/Getty Images)

The Rotunda, the most magnificent space in the U.S. Capitol, reopens to the public Thursday after a 19-day closure to have a circle of protective netting hung from its ceiling prior to the start of repairs to the cast-iron dome.

The netting, which resembles a huge doughnut, encircles the 149-year-old fresco, “The Apotheosis of Washington,” painted on the ceiling almost 200 feet above the floor. It is suspended from 12 hardened steel “outriggers,” Architect of the Capitol Stephen T. Ayers said at press preview in the Rotunda on Wednesday.

It is designed to catch any debris — up to 500 pounds — that might fall from the ceiling during the initial, $59.55 million phase of the multiyear project to repair the deteriorated outer surface of the dome.

The netting is similar to the system that was used in a 1999 lead-paint-removal project.

The Rotunda, a large, circular room at the center of the Capitol, has been closed to the public since April 12. It is a key stop on tours of the Capitol and features historic paintings and statues of presidents and other famous Americans.

Intensive care for a damaged dome

On the exterior, scaffolding already is going up to enable repair crews to work on the cast-iron covering, which has hundreds of cracks and crumbling ornaments that need to be fixed.

There were five layers in the netting system, the architect of the Capitol said.

The netting weighs 6,100 pounds and is the size of two tennis courts.

Some scaffolding was put up inside the Rotunda to protect the statues and paintings, and plywood was placed on the floor, but that will be removed in a few weeks.

Most, but not all, of “The Apotheosis of Washington” was visible through the central hole in the netting.

The netting will be in place for about a year and a half.

It paves the way for the “exterior scaffolding on the dome to move out apace,” Ayers said.

The overall dome project is expected to be finished in time for the 2017 presidential inauguration.

About 2.5 million people visit the Capitol annually. “It clearly represents who we are as a country,” Ayers said.

The Capitol represents our freedom, he added. “It’s our symbol of democracy, and it’s certainly seen that way around the world.”