What's the must-see thing in Toronto?

The CN Tower stands at 553 metres on the waterfront at 290 Bremner Boulevard, and on a clear day the observation level at 346 metres gives you sightlines to Niagara Falls, roughly 120 kilometres south. The glass floor section sits at 342 metres. You step onto it and your stomach drops, even though your brain knows the panel holds 14 adults' weight. The whole visit takes 45 minutes to an hour, less if you skip the gift shop. General admission runs CAD $43 for adults, CAD $33 for children aged 6 to 13, free under 5. Buy a timed ticket online to avoid the ground-floor queue, which can hit 40 minutes on summer weekends. Best time is late afternoon on a weekday, when the light shifts from white to amber across Lake Ontario and you can pick out the Toronto Islands clearly.

The Royal Ontario Museum at 100 Queen's Park opened in 1912 and holds roughly 13 million objects across 40 galleries. The Michael Lee-Chin Crystal addition, that angular glass-and-aluminium structure that juts out over Bloor Street, tends to split opinion. Some people find it aggressive against the original Italianate facade. Worth seeing either way. Inside, the Chinese Temple Art gallery on the first floor is the collection most visitors don't expect. The Futalognkosaurus skeleton in the Dinosaur Gallery hangs overhead, about 30 metres long. Adult admission is CAD $23, and the ROM sits directly at Museum station on Line 1, so you can walk from the CN Tower area in about 25 minutes via University Avenue or take the subway two stops from Union Station.

The Art Gallery of Ontario at 317 Dundas Street West, founded in 1900, holds over 120,000 works. The 2008 Frank Gehry redesign added the Galleria Italia, a 137-metre corridor of Douglas fir and glass that runs along Dundas Street. On Wednesday evenings from 6 to 9 pm, general admission drops to free. That's the move. The Group of Seven collection on the second floor, with Lawren Harris's North Shore paintings, likely won't mean much if you haven't spent time in northern Ontario. But the Thomson Collection of ship models on the lower level, with over 130 detailed miniatures, tends to hold people longer than they planned. The AGO is a 10-minute walk south from the ROM, so pairing them on the same day works if you start at the ROM by 10 am.

Mind you, Toronto's layout rewards a north-south pattern on your first day. Start at the CN Tower near Union Station, where the UP Express from Pearson Airport drops you in 25 minutes for CAD $12.35. After the tower, walk 15 minutes north through the Financial District to the AGO, then another 10 minutes to the ROM. By this point you've covered the core of downtown's grid and your internal map has started to settle. If June weather cooperates, with highs currently around 22°C and partly cloudy skies, the walk between sites is the best way to absorb the scale of the place. The streets smell like warm concrete and hot dog carts. You'll hear streetcar bells on Dundas. That said, if your legs give out, Line 1 connects all three sites and a single PRESTO fare is CAD $3.35.