Financial details were not disclosed.

The 36,000 m2 tower, which Patrizia bought from Banco Santander in 2016 for AIP Asset Managment, is leased until 2042 to Actiris, an agency of the Ministry of Employment of the Brussels Capital Region.

Wolfgang Kessler, a member of the management team at Union Investment Institutional Property, said: 'We are delighted to have secured this extremely sustainable office building for our institutional real estate fund. With its long-term lease and its prime office location in one of Europe’s most important markets, it ticks every box for a core investment.'

At 107 metres high and comprising 30 office storeys, Astro Tower has been a feature of the Brussels skyline since its completion in 1976. After undergoing major refurbishment in 2015/16, it received the highest possible level of energy efficiency certification.

The office is strategically located on the inner ring road, at the intersection of the three main neighbourhoods in Brussels’ central business district.

The asset has been acquired for the UniInstitutional European Real Estate fund, which has a volume of €3.7 bn. The fund already holds The Precedent (formerly Le Président) office building and a Motel One hotel in Brussels.

Added Kessler: 'The fund attracted significant inflows when it recently opened for investment, and this transaction allowed us to promptly invest the money raised in a cash flow generating asset with a very stable value.'

Said Kim Sardar, head of single asset mandates and director fund management at Patrizia, said: 'This sale marks the delivery of a successful round trip for our client, from acquisition in 2016.'

Danny Kim, CEO of AIP Asset Management, commented: 'The sale certainly demonstrated solid quality of the European assets with robust returns, further enhancing the level of interest in European assets among the Korean investors.'

Union Investment was advised on legal and tax aspects of the transaction by Stibbe, and on technical aspects by Bopro. Financial due diligence for Union Investment was conducted by RSM.

Patrizia’s advisors for this transaction include Savills, Knight Frank, Clifford Chance, TA Europe and Eight Advisory.