1. The city was built upon old Gold Rush ships.

During the Gold Rush of 1849, more than 500 ships were recorded to be in the city’s harbor as news of gold spread around the world. Many of the ships were immediately abandoned upon arrival and were left to rot. Others were transformed into saloons, hotels and jails, but eventually built over by the city. One of the most recent discoveries was in 1994 when a 200-foot long ship was found 35-feet underground during an excavation for a tunnel near the Ferry Building.

2. The San Francisco International Airport can move up to 20 inches during a quake.

Due to being in an earthquake-prone area, the city’s main airport is well equipped to handle any tremors. The entire airport is built on 267 columns that each rest on a five-foot steel ball that allows it to move with the quake. This brilliant innovation allows the building to separate from the movement on the ground. After an earthquake is over, the force of gravity will help the columns to re-center themselves.

3. Alcatraz was the only federal prison that provided hot showers.

Hot water was a luxury out on The Rock, but the reason for it was much less humane: it prevented the inmates from acclimating to cold water that could help them if they ever escaped into the frigid San Francisco Bay. This tactic must have worked since no inmate ever made a successful getaway.

4. The tap water is freshly melted snow from the Sierras.

The tap water in San Francisco has a distinguishable freshness to it since it’s sourced from the pristine mountain streams of the Sierra Nevadas. It’s recorded that about 85 percent of this drinking water is pure snowmelt. The Hetch Hetchy Dam was built in 1934 and continues to deliver top-notch water to millions of people in the city through an aqueduct that stretches for 280 miles.

5. The tide moves so fast in the Bay that boats can go backwards.

With all the water rushing into the Bay from the Pacific, the tide can be unpredictable and swift. During peak times the current can easily get up to 5 knots, which is twice as fast as a small sailboat can go. If the boat is turned against the current, it can begin to go backward. For kayakers, the situation is even less ideal and requires a lot of skill to maneuver the tiny boats back on track.

6. The real summer starts in September.

The city stays cool in the early summer with the constant fog layer that is present and only starts to heat up around Labor Day. Surprisingly, places that are more inland are reaching almost triple digits during the summertime, while in San Francisco and closer to the coast it can be a whopping 20 degrees cooler. The rule of thumb for summers in the city? Always keep a jacket nearby.

7. Dogs outnumber children here.

Walking around the streets, there’s evidence of an undeniable love of canines in the city. From dog-friendly bars to the numerous dog parks throughout SF, it’s no surprise that San Franciscans are big fans of man’s best friend. What is surprising though is that the amount of dogs outnumber the city’s children. Though when you stop to think about it, this makes perfect sense after you factor in the ridiculously high cost of living.

8. The BART subway trains have the longest life span in the country.

With more than 400,000 people riding this subway daily, there’s a lot of wear and tear. Despite general aging, BART has the trains with the longest running time of 30+ years. The runners-up are CTA in Chicago, which has an average of 26 years, and the MBTA in Boston, which has an average of 21 years. Of course, that says nothing about the cleanliness of the train, which is a whole different story.

9. The Sunset Neighborhood used to consist of mostly sand dunes.

This neighborhood that is famous for its fog and close proximity to the ocean, used to be mainly an oasis of sand. In the early days of the city, it was rumored that sometimes the houses were so few and far between that people would get lost for hours in the dunes with no landmarks to guide them back.

10. Vermont, not Lombard, is the crookest street in the city.

Although Lombard is the better known out of the two for being the crookest street in the city, Vermont has been proven to take the title. While Vermont may have fewer curves than its famous counterpart, it is steeper and is the site of the “Bring Your Own Big Wheel” Race, where participants race down the street on kid’s tricycles every Easter Sunday.

11. The “Summer of Love” actually started in the winter.

The famous social movement that embraced counterculture and free love started a few months before the summer of 1967, when there was a Human Be-In on January 14th at Golden Gate Park. This event drew approximately 30,000 people, who celebrate the new ideals of inclusive love and respect for all mankind, and was responsible for igniting the eventual hippie movement.