At this gorge, Colonel Walter O'Hara—an early 19th-century Irish settler who played a significant role in the establishment of the neighbourhood—led a regiment that fought against the retreating army of Napoleon.

Residential usage predominates along the west side, with some commercial storefronts around the intersection with Howard Park Avenue.

In 1856, the sons of Colonel O'Hara laid out Roncesvalles Avenue by dividing the lands along the street into lots.

In 1904, Joseph Phillips was owner York Region Loan and Savings Co. and had a five-story head office erected on Roncesvalles Avenue.

Using his connections, Smith arranged a streetcar line on Roncesvalles Avenue and the creation of Sunnyside Amusement Park.

[6][7] Between 2009 and 2011,[8]: 1  Roncesvalles Avenue was rebuilt to a new street design done after construction work to replace 100-year old water and sewer pipes as well as worn-out streetcar tracks.

The new street design included wider sidewalks made of paving stones with planters for holding 85 new trees, benches and "streetcar stop bumpouts".

[2][3][4] On December 19, 2010, 504 King streetcar service resumed on Roncesvalles Avenue after track replacement work and a redesign of the street.

[9] The new street design included bike lanes and a widened sidewalk "bumpout" at stops to allow riders to board streetcars directly from the curb.

In the interim, the TTC would operate a temporary shuttle bus between Dundas West station and Queen Street for those requiring an accessible ramp.