One of many ancient roman cities in West Tripoli, Libya features an impressive amphitheatre. Much of this city, which is just north of the Libyan Museum of ancient history, is still to be excavated.

Thanks: Mahmoud Swed

This is the utterly bizarre-looking Marin Civic Center in San Rafael, Califoria. Designed by America’s most famous architect Frank Lloyd Wright (although it wasn’t completed until after his death in 1959), the building featured in George Lucas’ other movie, THX-1138, and the (much better) sci-fi movie, Gattaca.

There’s some photo galleries well worth having a look at here and here, and there’s an excellent aerial fly-over gallery available here. The wikipedia page for the building currently has virtually no content, but fortunately the offical site has all the info you budding Wikipedians might need!

Thanks: William Kendrick, Leah Brooks, Eric Hegwer, Ross Burnett

You can see the Watts Towers in the centre of our thumbnail with shadows extending to the north. Compared to some of the towers we’ve previously featured, they look a bit, well, crap.

However, those other towers are all constructed by teams of engineers using cranes and scaffolding. Watts Towers were built single-handedly by a Mr Simon Rodia, over a period of 33 years. He began construction in 1921 and used junk steel, concrete, shells, glass bottles to create his towers. Pretty impressive.

The city was going to demolish the towers but public support forced them to reconsider. As a safety test a crane was used to shake the towers, yet none of them budged, and the test was concluded when the crane suffered a mechanical failure. The towers were deemed safe and have been preserved ever since. (Ground level pictures)

Thanks: Rob James & Robert Goddard

This is the absolutely stunning Roquefavour aqueduct, which carries water from the Durance over this valley in France. Built between 1841 and 1847, this incredible stone structure is a massive 83 metres tall. There’s lots more stats and a good photo over at Sructurae.

Our submitter also pointed us towards this perfectly conical tree, right in the middle of where no conical tree has any right to be. Apparently…

This is a quickly-maturing California redwood planted by the owner of the nearby house after a visit to California where he was suitably impressed by our wonderful giants

Many thanks to Paul Kim.

Villa Borghese is a beautiful park in the middle of Rome. Hovering above the ground is a large blue baloon which grants tourists a 360 degree view of the city.

Now, I don’t want to start a whole new 600 comment-long thread, but don’t you think this looks like a smaller, blue version of the old Google Maps UFOs?

Thanks: Leonardo Querzoni & Pedro Picotes