Underground Rail Is the Best Option
Because of track reconstruction at Willy-Brandt-Platz through mid-August 2025, trams aren't serving any stops close to St. Leonhard's Church, while Trams 12 and 14, which stop at Eissporthalle/Festplatz, near Holy Cross, are partly re-routed and don't cross from the city's west side. The project is also resulting in detours for car traffic throughout the city center. U-Bahn underground trains are stopping as normal at Willy-Brandt-Platz and Eissporthalle/Festplatz, so reaching St. Leonhard's and Holy Cross will be best by underground U- and S-Bahn lines.
Meanwhile, the Frankfurt City Triathlon takes place on Sunday, Aug. 3, 2025. Shutdowns of street traffic will be confined mainly to the city center and west and southwest sides, but may have some spillover effects on Holy Cross's neighborhood. German-language public-transport information is available at the VGF agency's website and the regional transport department at https://www.rmv.de/c/en/homepage/frankfurt.