In 1863, the Royal Botanical Gardens' Temperate House in Kew, England, opened to the public, a jewel of Victorian engineering and scientific thought. Flora from all over the world's temperate zones were planted in the greenhouse, and visitors who might otherwise never see such plants had a chance to stroll among them.

But 155 years is a long time, and the Temperate House was showing its age. A 2011 government report said a renovation was needed within three years if the structures were to survive. And so a massive restoration project commenced in 2013, the greenhouse draped in a tent large enough to house three Boeing 747s.

Now, the Temperate House has opened to the public again, with more than 69,000 elements removed, cleaned and either restored or replaced and 15,000 new panes of glass installed.

Horitcultural apprentice Emma Love waters replanted plants in the Temperate House
A number of plants have been replanted during the restoration of the Temperate House (Photo: Jeff Eden/Royal Botanic Gardens, Kew)

The gardens in the Temperate House also received a good cleaning as well.

For the first time since it opened, the beds of the garden were removed, including the soil. Ten thousand younger plants, as well as a few legacies, were then installed, many of them cultivated from cuttings of plants that had been in the greenhouse for decades. Those famous legacy plants were kept in a temporary nursery during the restoration process.

"It was heartbreaking to see some of the trees go," Greg Redwood, head of glasshouses at Kew, told The Guardian. "But some of them were hitting the roof, and it was very difficult to raise new specimens under the thick canopy.

"After years of pruning, a lot of the plants were effectively bonsais."

Encephalartos woodii, the 'loneliest plant in the world'
(Photo: Royal Botanic Gardens, Kew)

One of those legacy plants is the Encephalartos woodii, a tree that traces back to the time of dinoaurs. Considered the "loneliest plant in the world," the E. woodii is extinct in the wild and survives only in botanical gardens like Kew. The Temperate House's specimen arrived in 1899. The reason the tree is so lonely is because all the known trees are male. As such, the species is unable to reproduce naturally. Instead, botanists clone the tree.

Two other extinct-in-the-wild species are also housed in the Temperate House. Another 70 plants on display are either threatened or endangered.

Benches line the garden beds at the Temperate House
The plants at the Temperate House now must compete with the greenhouse's stunning architecture and views. (Photo: Gareth Gardner/Royal Botanic Gardens, Kew)

The Temperate House was designed by Decimus Burton, the same man who also designed the Kew Gardens' Palm House and buildings around Regent's Park and Hyde Park in London.

The Temperate House isn't as "experimental" in its design as the Palm House is, according to Apollo Magazine, but argues that Burton's "classical sensibilities are far more apparent in the more austere form and substantial decoration."

The total scope of the Temperate House — a main cathedral-like hall and two additional wings — wasn't all completed at the same time. The greenhouse only opened with the main hall in 1863. It would take almost 40 years before the north and south wings, called the Himalaya and Mexican houses, were both open. A teak annex was added in 1925. The whole complex stretches for almost 200 meters (656 feet).

The exterior of the Temperate House at Kew Gardens
The Temperate House is adorned with 'classical sensibilities.' (Photo: Jeff Eden/Royal Botanic Garden, Kew)

The interior of the Temperate House wasn't the only space that received a sprucing up. About 116 decorative urns along the exterior of the Temperate House were restored and replaced during the renovation.

"The restoration of the Temperate House has been a complex and immensely rewarding project, recalibrating contemporary understanding of Victorian architecture and the development of past innovations," the project's lead architect, Aimée Felton, said in a statement released by the garden. "New glazing, mechanical ventilation systems, path and bedding arrangements all took their founding principles from Decimus Burton's own drawings, held within Kew's archives."

A spiral staircase in the Temperate House
(Photo: Royal Botanic Gardens, Kew)

As budgets became crunched during initial construction and early renovation efforts of the famous structure, cheaper and cheaper materials were used. In the modern revamp, workers peeled back over 13 layers of paint in the oldest sections of the building, ranging from pale blue to cream to peppermint green. Now, the entire building is in a stunning white. The paint job required 5,280 liters of paint to cover 14,080 meters (46,194 feet) worth of surfaces. That's the same size as four soccer fields.

"The time it will take for the newly propagated plants to reach maturity will offer visitors a full and unobstructed view of the incredible metal skeleton in all its glory: a cutting-edge sanctuary for plants," Felton said.

An aerial view of the Temperate Garden's main area
(Photo: Jeff Eden/Royal Botanic Gardens, Kew)

And take time it will. The renovation of the Temperate House makes the greenhouse a generational attraction since it will take decades for many of the the plants to grow to their full splendor.

As The Guardian noted, "The future of the building has been secured, and, given that some of the plants won’t mature for another 25, 50 or 75 years, you can rest assured that your grandchildren will have the pleasure of seeing them at their best."

Here's to another 155 years, Temperate House.