An ancient and majestic fortress that played an integral role in Portugal's road to independence.

This eccentrically decorated palace is replete with grottoes, fountains, tunnels, and caves.

This unreal Portuguese palace looks as though it's made from a pile of different castles.

Hidden beneath a beautiful overlook you’ll find the history of the city depicted in comic strip format next to a pay toilet.

Elaborately carved to showcase the glorious wealth that the age of exploration brought to the Portuguese empire.

Twelve grave-faced marble angels guard the emperor's tomb at Les Invalides.

A little sculpture with a large wardrobe.

A much-maligned monument to teetotalism.

Rumor has it the uncarved lump behind the three famous suffragists is reserved for the first woman president.

The beloved statue at the National Academy of Sciences is oh so inviting to sit on.

The home of aviation trailblazers, in a remote corner of the big city.

The first piece of public art dedicated to LGBT rights.

This sculpture by artist Fritz Keonig survived the 9/11 attacks and now stands as a monument to the victims.

One of the most enjoyable bits of history at Coney Island and “the most romantic ride in the world.”

The original toys that inspired the beloved children's stories are on display at the New York Public Library.

One of only two commuter aerial tramways in the United States.

Elevated freight railway turned wildly successful urban park.

A crumbling hospital from the 1850s on Roosevelt Island.

This mosaic dedicated to John Lennon was tended for years by a Beatles super-fan.

An ancient underground cultic temple where sunlight penetrates on the summer solstice.

Descend 2,030 years into the past in an ancient tunnel built to support Jerusalem's most famous wall.

The National Railway Museum in York is the largest railway museum in the world, attracting almost 1 million visitors per year.

The railway carts travelers to central Athens's highest peak, which offers stunning vistas of the city.

This macabre masterpiece of a mural is one of Francisco Goya's "Black Paintings."