BTW, this post is almost 3 years old. I regret to say that the building is not in Second Life any longer. Instead, due to the lack of regular funding to pay tier, the project was moved to an independent OpenSim grid. This allowed it to continue — even if at a very slow pace — and expand. Now it's not just the Opera House that was recreated, but the surroundings too, all of which were destroyed, and which look quite strange to anyone who has visited the modern-day (i.e. post-1755) Lisbon. You can get a lot of images and some videos from the link.

Theoretically, if you're registered to any OpenSim grid that supports Hypergrid (almost all do), you ought to be able to teleport over and visit those spaces. Funding is being requested for another three years of work on this — expanding the city much farther and recreating 18th century events like (yes!) the two operas that were performed on the Lisbon Opera House in 1755. However, the sheer scale of the project — just for the “core city” we'll need some 16 sims or so — will sadly prevent this to continue to be offered on the SL grid It's either getting funds for research or development, or for paying tier. The team opted for allocating the funds, if they ever come, on research & development. Still, even without funds, some volunteers did continue the project (as the images show), albeit at a much slower pace.

The most remodelled building was indeed the Opera House I believe it's been rebuilt four times so far, based on continuing research: new documents explaining an obscure detail here and there which require a redesign (there are no paintings or engravings of the Opera House — in its 6 months of existence, nobody thought it was worth doing that at a rush! — or of its vicinity). The interiors will also need a complete redesign (for the fifth time!). So, yes, it's a work in progress. The irony is that it has taken now longer to recreate it in SL than in RL!