The Wallanlagen (lit., “Wall Park”) is a park area in Frankfurt which forms a nearly 5 km green belt around the city centre. It forms a semi-circle along the course of the former city walls, which were built from the 14th century, torn down in the early 19th century, and then made into a park between 1804 and 1812. The parklands are divided into seven areas, which are usually named after the former city gates: Untermainanlage, Gallusanlage, Taunusanlage, Bockenheimer Anlage, Eschenheimer Anlage, Friedberger Anlage and the Obermainanlage. Note: Anlage = Site.
This is a great way to run and see Frankfurt. The section of the park near the river is close to the older part of Frankfurt, while the ‘top’ skirts the newer part of the city, with skyscrapers and modern buildings. The Wallanlagen path is 4.3 km, and then 1.8 additional km along the river to make a full loop. There are lots of sites along the way. The medieval Eschenheimer Tor is at, 2.5 km mark, and just past there is The Old Opera.
Add-On: For a longer run, enjoy the paths along the Main river.