Big gun installations, built over a massive cemetery, now abandoned & hidden in trees.

Golden Gate Park's historic collection of plants.

The last remaining relic of San Francisco's glittering 1915 Panama Pacific Exposition.

San Francisco's newly reopened hands-on science museum.

Carnivorous plants, medieval aphrodisiacs, and the largest original wood structure glass conservatory in the western hemisphere.

Its buzzing collection honors vibrator history.

Relics of the 1894 Midwinter Exposition continue to delight visitors today.

Created in 1972, the famous sculptor's intricately detailed monument to San Francisco is overflowing with city landmarks.

Only hotel where you can legally launder money.

This abandoned viewing platform has become a monument to unnecessary government spending.

The final resting place of the great navigator, or maybe his brother.

This 18th-century project to build the world's tallest gravity dam was never completed.

This underground church is topped with a 500-foot cross that is seen by many as a beacon of fascist hubris.

This enormous censer uses a pulley system installed over 400 years ago.

These "mermaids" that surround a plaza in Segovia are rather sphinx-like.

This magnificent castle grew from a small Moorish fortress, and reportedly inspired two iconic Disney castles.

One of the few remaining ancient aqueducts described by Frontinus as 'the most solemn testimony of the Empire.'

The facade of this 16th-century building is decorated with carvings of 300 seashells.

Giant eggs, walls of bread, and nightmare surreality mark the largest collection of works by Salvador Dalí.

Spain's unique Mosque-Cathedral has been a place of worship for both Muslims and Christians throughout its history.

Cliffside houses provide a spectacular view from their perch above the valley.

These azure waters were thought to lead to the Mayan Underworld.

L. Frank Baum wrote part of the "Wizard of Oz" series in this wooden Victorian beach resort.

Dating back to the second century, vestiges of prehispanic mural paintings are found in this underground palace.