Olfactory delights in San Francisco's Botanical Gardens.

In all of the 29 years it was in operation, no prisoners ever escaped successfully... or so they claim.

A memorial in the Tiergarten is a reminder of the suffering inflicted on homosexuals by the Nazi regime.

Thousands of coffin-like pillars make up this controversial Holocaust memorial.

An impressive monument to Poland's independence.

The former Nazi Germany concentration camp stands as a museum to remember this dark chapter in European history.

Remnants from a time before electricity.

Poland's oldest surviving university building holds a wealth of historic science instruments including some used by Copernicus.

St. Mary's features one of the most spectacularly decorated cathedral interiors in all of Europe.

Atop this library is one of the most beautiful green spaces in Warsaw.

A tribute to the Polish insurgents who fought in the failed attempt to end their city's Nazi occupation.

In the summer, the area around this sculpture transforms into a vibrant concert venue.

The unique collection often goes unnoticed by visitors focused only on the archaeological objects.

A poignant museum dedicated to the history of the Dutch resistance against Nazi occupation

The world's oldest Jewish library was founded by Sephardic Jews in 17th century Amsterdam.

Cat art as far as the eye can see.

An ancient passage filled with stalls selling used books, once frequented by Vincent Van Gogh.

The mirrored section takes the shape of Hebrew characters when viewed from above.

Three connected pink triangles memorialize persecuted gays and lesbians throughout history.

This city square is home to Amsterdam's oldest church and a statue honoring Dutch sex workers.

The legend associated with these ruins understates the splendor of the mansion that once stood here.

Three columns of volcanic rock shoot out of the ocean.

A tiny village church in dramatic surroundings.

Along this wire fence, travelers have been leaving a particular memento since 2012.