The 130th running of the Boston Marathon takes place Monday, April 20, and the field assembled for it is among the deepest the race has seen in years. Twenty-six miles from Hopkinton to Boylston Street, Patriots' Day, the world's oldest annual marathon. If you follow distance running at all, this is the week you pay attention.

The defending champions — Sharon Lokedi and John Korir, both of Kenya — are back to defend their titles, a rare occurrence at a race that more often crowns first-time winners. Lokedi won last year with a performance that silenced a field of Olympians. Korir's victory was a front-running display that made the race look easy until, suddenly, the hills made it look very hard.

The course itself is the story Boston tells every year. The Newton Hills — four climbs in the final third of the race, capped by Heartbreak Hill at mile 21 — have ended more title bids than any competitor on the start line. Athletes who run the early miles conservatively tend to run the late miles faster. Athletes who do not tend to be interviewed on the side of the road.

Weather projections for Monday call for cool temperatures and a modest tailwind — conditions that favor fast times. The women's course record, set in 2011, has stood for fifteen years and feels perpetually vulnerable on days like this.

Coverage begins early Monday morning. The elite women start at 9:32 a.m. ET, followed by the elite men at 10:00. The finish line on Boylston Street is, as always, worth watching.