Local studio PGM Arquitectura has completed a series of garden suites on top of the podium of the St Regis hotel skyscraper in Mexico City, originally designed by Argentine-American architect César Pelli.

Hotel chain St Regis brought on PGM Arquitectura to refresh the interiors of the skyscraper in Reforma, one of the city's central business districts. The studio had previously carried out designs for the hotel's restaurant.

The 150-metre-tall César Pelli-designed skyscraper was completed in 2008 but the team at St Regis found that its interiors had become dated. The hotel wanted to update them to keep pace with the growing tourist industry in the city.

The skyscraper has a fourth-floor podium, after which the glass-clad spiral structure steps back and continues its climb toward the sky.

PGM Arquitectura founder Patricio García Muriel told Dezeen that this was the best place to demonstrate the potential of the hotel's interiors, which the studio plans to completely revamp in the next few years.

"There was a rooftop on the fourth floor, which was horrible," he said. "Those rooms on the fourth floor were the worst in the hotel."

The studio transformed the eight suites on that level, turning the rooftop into garden terraces for guests.

The largest suite, the two-bedroom Caroline Astor Garden Terrace Suite, now wraps around nearly a quarter of the building and comes complete with an elevated infinity pool.

Before construction commenced, PGM Arquitectura had to carry out a full structural analysis to determine that the terrace could hold the massive pool without altering the exterior of the iconic Mexico City tower.

"It's a very solid building," said García Muriel. "It has sustained through all the major earthquakes in Mexico."

All of the suites include pergola and privacy screens made from stacked pale-coloured bricks to shield guests from onlookers in the surrounding tall buildings, especially on the side facing the denser areas of Reforma.

The other side has terraces that are "much more open", according to García Muriel.

Inside the suites, PGM Arquitectura stuck mostly with the scheme used for the original interiors by Canadian studio Yabu Pushelberg, keeping the lilac and white hues of the walls.

However, the studio swapped out the carpet that had lined most of the floors – a move it plans on continuing for the rest of the hotel. Details in the rooms and throughout the PGM Arquitectura-designed spaces were informed by the Mexican landscape, with tactile surfaces, gold finishes and colourful wall hangings.

The terrace serve to create a kind of "oasis" in the bustling city, García Muriel said.

"You can get away from the city, with it still being there," he said. "You're in the city surrounded by buildings, but you're in an outside protected area with a lot of privacy."

Pelli's studio Pelli Clarke & Partners recently completed a similarly shaped skyscraper in the southern part of the city, which is now the tallest skyscraper in Mexico City.

The photography is courtesy of St Regis Mexico City.