In the lead-up to the first Boston Marathon since last year's deadly attack, much has been said about the symbolic importance of this year's big run. A few participants in the upcoming marathon share why Boston is such an iconic and difficult course for runners.

The basics:

The basics of the course are pretty well known. 26.2 miles. One of the world's oldest annual marathons. Part of the yearly Patriots' Day celebration in Boston, which draws as many as 500,000 spectators each year. (Over one million are expected to attend this year.)

The course ends in the heart of Boston, but encompasses a number of small cities and towns outside Boston proper such as Natick, Newton, Framingham, and Brookline. 

The route:

The route itself can be particularly deceptive. It starts with a long stretch of downhill running, which can lull a runner into a sense of complacency—you know, as much as marathoners can be complacent about anything—or entice them to run faster than they should.

Albert Rubinsky flew up from Texas to run in his second Boston Marathon (2012):

A lot of people don't realize that most of the race is actually downhill. Overall, the Boston Marathon course has a negative net elevation. One problem is that people go out way too fast at the beginning of the race. Enthusiasm, crowd participation, and the early downhill miles make a compelling argument for starting fast."

Elizabeth Johnston, also in her second Boston Marathon (2013), described how the route changes around Mile 16, leading the course into a series of four hills and drops around Newton. Training for Boston requires a different regimen than training for flatter terrains like, say, Houston.

"Last year, I really trained on hills. This year, I know the crowd support will be fantastic and I'm hoping that gets me up Heartbreak Hill."

Heartbreak Hill:

One of the Boston Marathon's signature challenges is the final of the four Newton hills. Heartbreak Hill gets its name in part from the fact that it's situated near the end of the marathon's 20th mile, just when runners are hitting the proverbial wall. 

Rubinsky, who trains in Austin, Tex., a city with no shortage of hills was set back at Heartbreak Hill in 2012, a marathon that broke the all-time record for high temperatures (87 degrees). 

Rubinsky sent along a graph of his 2012 run, which showed him running at an ungodly pace for the first 20 miles before he was eventually slowed (I mean, by a runner's standards at least) to a ten-minute mile after completing Heartbreak Hill.

"I know now that I definitely was not taking enough fluids, and I absolutely should have worn a hat to protect my head and face from the sun."

Our mothers would agree. (Weather forecasts for tomorrow are much more forgiving with temperatures expected to climb into the 60s in the afternoon.) 

From there, the course wends into way into Boston. Marathoners are greeted for their final mile by Boston Red Sox fans who walk/stagger from a home game at Fenway Park that is scheduled for the late morning each year on Patriots' Day.

The marathon finishes with a stretch down Boylston Street and ends, with great ceremony, just short of Copley Square near the Boston Public Library.