One of those quite literally “once in a lifetime” opportunities comes to an end in just three months time.

The Painted Hall in Greenwich, often described at Britain’s Sistine Chapel is currently undergoing restoration, so the entire inside of the main hall of this Sir Christopher Wren and Nicholas Hawksmoor designed building is covered in scaffolding.

And, if you choose, you can climb the metal stairs and get right up to the ceiling and see the restoration work with an intimacy that is otherwise impossible to achieve.

Getting up close to the detail of the painting reveals the genius of the painters, who while working up close to the finished work were also having to paint for a viewer who would be standing 60 feet below them. It’s a mix of almost crude decoration that’s going to look exceptionally polished from the ground level, to amounts of fine detail that it must have been impossible for people to see from the floor.

Do look out for the vandalism from a previous restoration, when someone wrote their name right across Queen Anne’s cleavage. A detail like that can only be seen when right up close to the ceiling. Which is fortunate for the previous restorer, who left his mark for posterity in the bosom of a Queen.

The restoration will be completed in three months time, and it’s unlikely that there will be any more work needed on the ceiling for at least 100 years.

So, this isn’t just a once in a lifetime opportunity, but one that several generations to come will not be able to experience. The next time restorers need to get to work, they’ll probably fly up on anti-gravity hover boards.

Tours with a guide to point out the best bits cost £11 and can be booked here.

The last tour takes place on 30th September, so you don’t have long before this opportunity to get up to the ceiling is lost forever.

The Painted Hall restoration project is has raised most of the money it needs, but is still fundraising to complete the works, and you can sponsor a square foot of restored paintwork for £75.

The restored Painted Hall is due to open in 2019, then once more apart from visits to admire it, every January, you’ll be able to raise a glass of port and toast the Immortal Memory of Admiral Lord Nelson under that magnificent ceiling.

But more below ground

While the ceiling is getting a few decades of grime removed, they are also working on a brand new visitor centre, in the undercroft area. This renovated space had to be changed slightly from the original intention when one of the most significant Tudor finds of recent years was discovered.

The Old Royal Naval College sits on top of a huge Tudor palace, of which very little remains, but under the Painted Hall, they discovered the remains of a brick cellar, and some wonderful floor tiles.

What makes it stand out are the niches, which they now believe to be bee boles, or storage spaces for early bee hives which were brought indoors in the winter months. While many rich gardens have bee boles in their garden walls, only the richest could afford a cellar, and for so many bees. Truly a cellar for a king.

Having discovered the cellar, the restored undercroft has been altered to show off the discovery, and a glass balustrade will run around a new oval hole in the floor where visitors will be able peer down into the depths of Tudor history.