The ARTIFICIAL tree is 75-metres high Europe's tallest artificial Christmas tree was erected at LISBON's Praca do Comercio, a traditional 18th century square, also known as Horse Square was switched on Nov 25th 2006
UK's tallest REAL Christmas tree installed at More London Saturday 13 December 2003 London SE1
Over 5,000 multi-coloured lights lit UK�s tallest Christmas tree. At well over 80ft the Scottish-grown Sitka spruce stands proudly in the Pool of London at More London, the 13-acre riverside development near Tower Bridge.
I would say LISBON