As 36,000 marathoners get ready to pound the streets of Boston on Monday, authorities have their own mammoth task ahead: trying to keep all 26.2 miles of the course safe.
Officials say they have gone to great lengths to make sure nothing like last year's attacks will happen.
For starters, no backpacks or rucksacks will be allowed on the course this year, said Kurt Schwartz, director of the Massachusetts Emergency Management Agency.
The bombs that killed three people and wounded 264 others last year were placed in backpacks.
The Boston Athletic Association, which organizes the marathon, said spectators are also encouraged to leave backpacks and handbags at home.
Containers with more than 1 liter of liquid, costumes covering the face, and bulky clothes such as vests with pockets won't be allowed.
And large flags or signs bigger than 11 inches by 17 inches are also banned from marathon venues. Those venues include the start and finish areas, the course, the athletes' village and areas where official events are held.
Unregistered runners and cyclists intending to jump into the race aren't welcome this year, either.
"We are aware that many people want to participate in some way in this year's Boston Marathon as a display of support," the BAA said in a statement. "But we ask that those who are not official participants to refrain from entering the course for the safety of the runners and themselves."
The anniversary scare
At a memorial to mark the one-year anniversary of the bombings, one sight evoked memories of the gruesome attacks: suspicious bags near the Boston Marathon finish line.
Police spotted the bags on Boylston Street -- not far from where two pressure-cooker bombs exploded a year ago.
The first clue that something was amiss came when an officer spotted a man carrying one of the bags walking barefoot in the rain down Boylston Street. Police said he became very vocal and started yelling.
When asked what was in his backpack, the man told the officer it was a rice cooker, Boston Police Superintendent Randy Halstead said.
"We looked into the backpack, saw that it was what appeared to be a rice cooker, had the individual take the knapsack off, drop it on the street, and he was taken into custody," Halstead said.
The man was identified by prosecutors as Kevin Edson, also known as Kayvon Edson. He was arrested and charged with disorderly conduct, disturbing the peace and possession of a hoax device, Halstead said.
A bomb squad inspected the bag and deemed it safe.
"In the process of rendering that safe, we noticed a second backpack off to the side," Halstead said. "Nobody claimed ownership of it. At that time, that bag was rendered safe."
Halstead said his officers are ready for this year's marathon. In Tuesday's incident, he said, the "training kicked in."
"I have utmost praise for my officer," Halstead said. "That's what he's trained to do, that's what he did, and that's why I'm proud of the guys of this department."
A massive enterprise
This year's marathon will be a massive enterprise.
The race will have 9,000 more runners than last year. More spectators than ever before will also line the course, according to the Boston Athletic Association.
Keeping that in mind, police will double the number of officers on patrol from last year, with 3,500 scattered among the crowd. They will be aided by 100 additional security cameras and bomb-sniffing dogs.
"In this world, you never eliminate risk; you never bring it down to zero," State Police Col. Timothy Alben told reporters last month. "But we are working very hard at reducing that risk level and managing it to the best of our collective abilities."
Authorities have not disclosed how much the extra security will cost. All they will offer is that it will be "much greater" than last year's cost.
But this year's race will also reap millions of dollars. According to the Greater Boston Convention & Visitors Bureau, the marathon and related events will bring in an estimated $175.8 million -- the highest-ever amount for a Boston Marathon.