Horseshoe Falls is the defining natural landmark on the Canadian side of Niagara Falls. Treat it as an outdoor viewing destination rather than a ticketed attraction: the best visit is shaped by your approach, the weather, and how much time you want to spend along the parkway.
Build in time to walk the viewpoints and expect spray close to the crest. Niagara Parks says entry to its parks is free, while most parking lots are paid; individual nearby attractions keep their own schedules and admission.