The Ritz in London is planning a major redevelopment to compete with other luxury hotels across the capital.
The plans, first reported by the Evening Standard, are estimated to cost £300m and will take over three and a half years to complete.
Documents show the Grade II-listed hotel, founded in 1906 by César Ritz, is seeking to construct a five-storey basement extension that will include a two-storey pool, gym and spa.
It will also feature underground parking for 10 cars to accommodate VIP guests, which the hotel said includes the Royal Family and international heads of state. An additional 53 bedrooms will be built, 10% of which will be wheelchair accessible.
The hotel currently has 138 rooms and features the Michelin-starred Ritz Restaurant, the Rivoli Bar, Ritz Club and cigar shop.
An application made on behalf of the Ritz argues that despite major refurbishments taking place in the 1970s and 1980s, the hotel has not been upgraded for decades and has fallen behind the "standards for luxury hotels".
The aim is to upgrade the property to become one of the most luxurious hotels in the world.
Proposals include extending the main building at roof level to the Arlington Street Wing, while the basement extension will be constructed on the site of Eagle Star House, a 1970s office block which is being demolished.
Westminster City Council planning officers have recommended approval of the plans, which will go before a committee next week.
The extension will be internally linked to the existing hotel, where the main entrance, restaurant, bar and function rooms will remain unchanged. No additional bars or restaurants are proposed in the application.
The plans come after the hotel was sold to Qatari tycoon Abdulhadi Mana Al-Hajri for around £700m in March 2020. It was previously owned by the Barclay brothers, who paid £75m for the hotel in 1995.
A spokesperson for the Ritz said: "We are excited about the forthcoming development of The Ritz London that will continue to evolve the vision of our founder, legendary hotelier César Ritz.
"This inspired project will ensure that the unique essence of the hotel is retained, sympathetically restored and further enhanced to reaffirm its status, for generations to come, as one of the world's most iconic hotels."