Complex sentence: The canals on the site that opened in 2014 are frozen for skating and other winter activities by an underground refrigerant plant housed in a rebuilt sub-basement that was part of Memorial Auditorium and a marker on the canal ice denotes center ice's location.
Split into simpler sentences: The canals on the site opened in 2014, and they are frozen for skating and other winter activities by an underground refrigerant plant housed in a rebuilt sub-basement that was part of Memorial Auditorium. In winter, a marker on the canal ice denotes center ice's location.