This city's famed marijuana bars have weathered many challenges over the years and are still smoking, blanketed in reggae music and a skunky haze.
But now they face an unwelcome blast of fresh air: On July 1, the Netherlands will be one of the last European countries to comply with EU law and ban smoking in bars and restaurants.
The Health Ministry has made it clear the ban will apply to cafes that sell marijuana, known as coffee shops. But this being Holland, which for centuries has experimented with social liberalism, there's a loophole: the ban covers tobacco but not marijuana, which is technically illegal anyway.
But that still leaves coffee shops and their customers in a bind. Dutch and other European marijuana users traditionally smoke pot in fat cone-shaped joints mixed with tobacco.
Shops are scrambling to adapt. One alternative is "vaporizer" machines, which incinerate weed smokelessly. Another scheme is replacing tobacco with herbs like coltsfoot, a common plant similar to a dandelion in appearance that smokers describe as tasting a bit like oregano.
But most are just planning to increase their sales of hash brownies and pure weed - and hoping the law isn't enforced.
Michael Veling, owner of the 4-20 Cafe and a board member of the Cannabis Retailers' Union, said he expected a small decline in sales as smokers are forced to separate their nicotine addiction from their marijuana habit.
But he expects the long-term effects to be minimal. "It's absurd to say that coffee shops will go bankrupt in the second week of July. Nonsense."
Veling is instructing his staff to send tobacco smokers outside, but he doesn't expect all coffee shops to do the same. He said some owners will ignore the ban - and probably get away with it, at least for a while.
But "if obeying the smoking ban becomes a condition of renewing your business license, just watch how fast it will happen," he said. "That's the way things work."
Jason den Enting, manager of coffee shop Dampkring, said it would be impossible to monitor what customers are smoking.
"It's the world upside down: In other countries they look for the marijuana in the cigarette. Here they look for the cigarette in the marijuana."
Chris Krikken, spokesman for the Food and Wares Authority, charged with enforcing the ban, said his agency won't be targeting coffee shops in particular.
"For the first month we'll just be gathering information about compliance in a wide range of hospitality businesses. Depending on what we find, we may focus more squarely on a sector that's lagging."
But he said individual businesses caught allowing customers to smoke will be warned and definitely checked again. "Repeat offenders will face escalating fines," he said.
Marijuana possession is illegal in the Netherlands, but smokers are not prosecuted for holding up to 5 grams. Around 750 cafes - half of them in Amsterdam - are licensed to have up to 500 grams in stock at any one time.
The Dutch "tolerance" policy is a pragmatic recognition that people will smoke pot regardless of laws, so it might as well happen in an orderly way. Critics complain this encourages substance abuse.
But the use of cannabis in Holland ranks somewhere in the middle of international norms: higher than in neighboring Germany but lower than in France, England and the U.S.
At the same time, the levels of THC - the main active chemical in marijuana - have soared in the past decade and are now at 16 percent in Dutch weed.
The U.S. government sounded the alarm earlier this month because THC in American marijuana has doubled to 9.6 percent since 1983, and it warned of recent scientific findings linking the drug to mental problems.
The Dutch government, currently led by a conservative coalition with a religious bent, is slowly squeezing back the number of coffee shops by not renewing licenses when shops close.
Growers are arrested, leaving coffee shop owners struggling to obtain their main product.
"The rules are being set to pester us out of business one by one, slowly but surely," said Richard van Velthoven, manager at The Greenhouse, who said he feared being shut down for tobacco violations.
"I've taken the cigarette machines out, I'm putting Coltsfoot on the tables, I've bought extra vaporizers, the staff is watching out - what more can I do?"
German tourist Lars Schmit said lamented the possible end of an era.
"Amsterdam has a lot of other things that are nice: you can party, it's funny to see all the people riding bicycles, it's completely different to other places, but if the coffee shops go away, it's not the same," he said.
Without coffee shops, he said, "a little bit of Amsterdam will die."