The hook
A city park about five hundred acres larger than Central Park, containing a zoo, an art museum, a science centre and a history museum — all of which are free, permanently, to everyone.
01Why it's worth it
The free part is not a promotion and it is not a suggested donation. St. Louis funds these institutions through a dedicated regional tax district, so the Saint Louis Zoo, the Saint Louis Art Museum, the Missouri History Museum and the Saint Louis Science Center charge nothing at the door. For a city of this size that is close to unique in the United States, and it changes how you use a day here: you can go into the art museum for forty minutes to see one thing and leave without having spent anything, which is not how most people are able to treat a major collection.
The park itself is the residue of the 1904 World's Fair, which was held here alongside that year's Olympic Games. The Art Museum occupies the Fair's Palace of Fine Arts, the only major structure built to last — it sits on a rise above the Grand Basin with Saint Louis on horseback out front, and the view back down over the water is the classic one. The 1904 Flight Cage, built by the Smithsonian for the Fair, is still standing in the zoo and is still in use.
Beyond the institutions it works as an ordinary park: a boathouse with rowboats, a golf course, running paths, a lake system, and the Muny — an 11,000-seat outdoor theatre that has run a summer musical season since 1919 and keeps around 1,500 seats free every night.
02How to experience it
Give it a full day and treat the museums as drop-ins rather than expeditions. Art Museum in the morning, walk down to the Grand Basin, zoo in the afternoon. Rent a boat if it is warm. The park is large enough that walking end to end eats time; the free shuttle loop is worth using.
From the locals
The free-ness is what locals lead with, every time, and they are specific about it. "The nicest thing about St. Louis is that there is a lot of free or very cheap things to do. The history and art museums are free. The zoo is also free and right by the art museum. All these places are in Forest Park." That commenter adds two things visitors miss — a new playscape near the zoo, and Kennedy Woods behind the art museum.
Another, recommending the city to someone driving all fifty states: "everything in Forest Park is free, so you can go to the zoo, art museum and science center all for no charge. Furthermore, Forest Park is an amazing and massive city park right in the middle of the city."
A third calls it "overflowing with free museums, our free world-class zoo" — note the our.
A St. Louis local answering a trip-planning question on r/solotravel put it ahead of the Arch outright: "Forest Park is amazing — it's a huge city park with a bunch of free stuff in it," with one instruction attached: "make sure you visit the art gallery while you are at Forest Park." Both locals in that thread mention the Arch too, and both are lukewarm about it. The park is where residents actually send you.