In the 1920s, the neighborhood was known for being a happening place with speakeasies and boxing gyms. Nowadays, it is a popular place for musicians and especially jazz clubs. It used to be populated primarily by single people but is now a family neighborhood as well.
Walking through Tenderloin is very urban, offering high-rises and apartment buildings that open right onto the sidewalk which has no divider between sidewalk and road. Lots of restaurants in the area with outdoor seating will provide you and your pup a break from walking through the heavy pedestrian traffic if your dog should become overwhelmed. In general, this will be a tight walk with a few sloping hills here and there.
The San Francisco Civic Center historic district offers grassy fields that you and your dog can enjoy, but the lack of tree cover means that this is a hot destination on warm San Francisco days. The coast is not far from this neighborhood and offers a walk along the water with lovely breezes, as well as more regional parks than you will find in the rest of the area. You can also cross the bridge and find your way to Yerba Buena Island for different terrain.
There are not many green spaces around Tenderloin as this is a dense city area. One little regional park just outside of the neighborhood, Jefferson Square Park, offers grassy areas as well as a few trees for shade. Lafayette Park is not far either and also offers a nice tree covered area as well as grassy places. Corona Heights Park, as well as Buena Vista Park, are next to each other and both offer lots of varied terrain over mountainous areas with alternating sandy desert spaces and dense forest. Trails cutting through this forested and rocky area make for a safe walk.
If you are willing to drive for even more exploration, you can head towards Presidio and all of the wilderness as well as the gorgeous beach here, or you can go to the Golden Gate Park which offers beautifully manicured trails around water features and grassy fields.