The Infinity or 300 Spear Street is a mixed-use residential condominium development in the Rincon Hill neighborhood of San Francisco, California consisting of 2 high-rise towers and 2 low-rise buildings. The four buildings contain 650 residential units. The complex is the first phase of a massive residential development encompassing two city blocks.

Rincon Hill is a neighborhood in San Francisco, California. It is one of San Francisco's many hills, and one of its original "Seven Hills". The relatively compact neighborhood is bounded by Folsom Street to the north, the Embarcadero to the east, Bryant Street on the south, and Essex Street to the west. Named after Rincon Point that formerly extended into the bay there, Rincon Hill is located just south of the Transbay development area, part of the greater South of Market area. The hill is about 100 feet tall.