Mexico is one of the more relaxed countries in Latin America for LGBTQ+ life — same-sex marriage is legal nationwide — and Mexico City has a few well-known outdoor cruising spots, mostly in and around the historic centre.
Alameda Central, the park just west of Bellas Artes, has a long history as a daytime meeting point. The streets around the La Ciudadela market are also known, though this area sees petty theft, so keep valuables out of sight and stay aware after dark. Further south, the wooded paths around Ciudad Universitaria (Camino Verde, near UNAM) draw a student crowd.
Standard common sense applies: these are public spaces, so read the situation, watch your belongings, and avoid isolated corners late at night. For indoor alternatives see the saunas listings and the Gay Mexico City Guide.