San Francisco is often referred to as one of the most beautiful cities in the world. Those of us fortunate enough to live here enjoy year-round moderate temperatures, mountains, ocean, fog, and that delicious and pervasive scent of eucalyptus.

But living here isn’t cheap, so we spend a lot of time working long hours indoors, staring out our office windows longingly between meetings and emails, and wishing we could be doing something—anything—outdoors. So after a long hard week of work, treadmills, elliptical machines, and free weights, many San Franciscans get outside to add a little green to their weekend exercise routines. One of the most beautiful (and physically challenging) places to do this is the Lyon Street stairs.

“Green” stairs, you ask? Absolutely. The stairs are nestled next to The Presidio, which makes all that heavy breathing you’ll inevitably end up doing that much more pleasurable thanks to the heavenly smell from the Presidio forest. The elevation of Broadway Street (the top of the stairs) and Vallejo Street (the middle, before heading down to Green Street) provides an amazing view of the Bay and the mountains of Marin County. Along both sides of the stairs are all kinds of flowers and foliage I couldn’t begin to name, creating one of the most stunning places to exercise (or read, meditate, or just relax) in the city.

But don’t let all this flowery, green goodness fool you. No matter what your fitness level, these stairs will kick your ass—and your abs, calves and thighs, too. There are 288 stairs total and whether you walk them or run them, you will be sweating and breathing hard. Every time I come back to the Lyon Street stairs, I’m reminded of how exercising on a Stairmaster in a gym has fooled my body into thinking that climbing stairs is anything other than downright grueling. Here, there are no rails to lean against, there’s no button that will allow me to lessen the resistance. It’s just me and my fully upright body, running (okay, mostly walking) one step at a time, flight after flight, until my legs are shaking like freshly-boiled spaghetti noodles.