Like an episode out the show "This Old House," some major renovations are about to take place directly beneath the golden dome of the Massachusetts State House.

A much-needed overhaul of the Senate chamber is about to begin at a cost of about $14 million. (With design, the full price tag is nearly $23 million.) The room is located in the 219-year-old "Bulfinch Front," the oldest and original part of the State House, designed at the end of the 18th century by Charles Bulfinch. So, in addition to bringing the place up to code, architect Christos Coios, of CBT Architects, says preserving the history is a challenge.

"While you learn the history of the room, you learn the history of the state. So we found that extremely interesting," Coios said. "Partly because we had to recreate it, there were no drawings, there was cartoon images and anecdotal information and written reports but very little in the way of visual images."

Paint peels away from cracked plaster behind the Benjamin Franklin bust in the Senate chamber. (Robin Lubbock/WBUR)

Since the mid-19th century, the walls of the chamber have been made up of more than 1,500 wood blocks, attached to wooden strapping. Over the past 150 years, the blocks have been painted at least 20 times, and the structural integrity of the walls has become compromised. When construction begins, each of those blocks will be removed, numbered and then stripped down to bare wood, before being given a fresh coat of paint. And then like a giant jigsaw puzzle, they will be securely restored to the exact same position.

Desks in the room will be brought up to standard of the Americans with Disabilities Act, and the president's rostrum, now only accessible by stairs, will become completely accessible with a small lift installed behind the rostrum. Other upgrades include improved acoustics, better lighting and more efficient HVAC.

"Oh, this is a huge project," said Senate President Stan Rosenberg. "I've been involved in several home renovations and they're exciting, exhilarating, challenging, frustrating and when it's over, spectacular. We hope we'll have very little of the early part of that string, and that it will be spectacular when it's finished."

For the next year and a half, the Senate will be operating out of temporary quarters in the sub-basement of the State House's east wing. The project is scheduled to be finished in January 2019.

Architect Christos Coios points at areas in need of repair in the State House Senate chamber. (Robin Lubbock/WBUR)

Correction: An earlier version of this report just included the construction costs, which are estimated at about $14 million. The full price tag, with design, is nearly $23 million.