The 68x80m Ecotrack arena will make Windsor “as weather-proof as it can be”, said event director Simon Brooks-Ward.
Work began earlier this month and will be complete for the Royal Windsor Show (13-17 May).
The new arena will sit next to the existing all-weather main ring, and the two will hold around 70% of competition at the show.
The ground at Windsor faced criticism in 2005 after horses appeared lame while in the ring.
Mr Brooks-Ward said: “The improvements are good news for all competitors.”
• The entries deadline for the May show has been extended until 3 April. For tickets visit: www.rwhs.co.uk
This article was first published in Horse & Hound (26 March, ’09)