Monsanto Tower, Modern tower in Algés, Portugal

Monsanto Tower is a 120-metre office building in Oeiras, west of Lisbon, with 20 above-ground floors and 2 underground levels. Designed by Sua Kay Architects and built by Mota-Engil, it was completed in 2001 and has 12,780 square metres of office space. It is the second-tallest building in the Lisbon region.

Monsanto Tower was built in the late 1990s and opened in 2001, during a period when the western suburbs of Lisbon were growing quickly. The Oeiras municipality was attracting new business investment at the time, and the tower was part of that wave of construction.

The Monsanto Tower stands in the business district of Algés and is a good example of late 1990s office architecture in the Lisbon suburbs. Its glass and steel profile is easy to spot from the highway and from the Tagus River.

Algés has a train station on the Cascais line, which connects the area directly to central Lisbon, making the tower easy to reach without a car. The surrounding streets are open and easy to walk, so the building can be seen clearly from the nearby roads and the riverfront.

A second tower was planned: Monsanto Tower II, also designed by Sua Kay Architects, would have risen 73 metres with 21 floors above ground. The project was proposed in 2002 but was never built, so the single 120-metre tower remains the second tallest building in the Lisbon region.