Plans have been lodged by the National Trust for Scotland (NTS) to build a vertical gallery and bird hide in a 19th-century botanical garden in the country's Highlands.

London-based architects Denizen Works are behind the proposal for Inverewe Garden, which was first opened in 1862 and features more than 2,500 exotic plants and flowers.

The 20m-tall (65.6ft) tower is designed as a "landmark and orientation point to encourage more people to visit the far reaches of the garden". Based in the idea of a "sliced tree trunk", the building will be clad in dark, stained larch conifers, which will be sourced on site. Internally, timber board is left exposed, "providing a warm and light counterpoint to the totemic presence of the tower".

"Our response to this open brief from the National Trust for Scotland saw us explore the history of Inverewe and take inspiration from the natural world," said a statement from the architects.

"Combining the rich artistic heritage of the garden with nesting forms of local wildlife has resulted in proposals for our vertical gallery and bird hide."

The structure's form is inspired by a "burrow or woodpecker’s nest", with internal functions not necessarily understood from the outside. The experience, says Denizen, is integrated in the natural root through the garden's landscape.

"Forming part of a route, the tower is accessed from a high viewpoint, where visitors will follow a path down the natural contours before crossing a short bridge to the tower," said the architects.

"The staircase links to a further network of paths at the base via gallery spaces telling the story of the garden through different spatial experiences at each level, combined with art specially commissioned for the tower."

The structure features a bird hide at its peak, offering views of the surrounding tree canopies and allowing visitors to observe the local wildlife, including nearby nesting herons and local golden eagles.

“We’ve seen a surge in visitor numbers at Inverewe thanks to our recent investment including the renovation of Inverewe House, the development of the new Sawyer Gallery and Bothy Café, as well as new glasshouses," said Clea Warner, general manager for the North West at NTS.

"This next phase of development at Inverewe will make it an even more popular place to visit while protecting the landscape now and for future generations to come.”

Planning has been submitted to Highland Council, with work to start in Q3. The project is expected to be complete by the second quarter of 2019. The project is part of a wider effort by NTS to invest £57m (US$75.4m, €64.5m) enhancing the visitor experience and condition of heritage at the sites and properties it protects.