This hole, called Confluence, features a surface that changes color as you play. Watch that your ball doesn’t get stuck in corners. (Fritz Hahn/The Post)

The National Building Museum’s Mini-Golf in the Museum, which runs through Labor Day, is one of the most attractive and imaginative mini-golf courses I’ve seen. Each of the 12 holes was created by architects and contractors (this IS the building museum). STUDIOS Architecture’s hole is based on their design for Canal Park in Southeast Washington. JBG and the Landscape Architecture Bureau invented a forest of helium balloons atop tall metal poles that block the hole.

There are wooden streetscapes where you putt down bike lines, maps of Washington where the streets have become little gullies that lead to holes, even a stone labyrinth. Some of the course works better as demonstrations than playable golf holes -- try the skateboard halfpipe where the cups are mounted halfway up the walls -- but they are all generally fun to play, and at $5 ($3 with a museum ticket), it’s pretty cheap.

This hole, canal PARk, was inspired by the outdoor architecture planned for Canal Park in Southeast Washington. The glowing cube contains a hole that drops the ball to the lower level. (Fritz Hahn/The Post)

Admission isn’t timed, so there are long lines to get in to the three-room gallery where the course is located. By the time a hooky-playing friend joined me at 2:00, there was a 20-minute wait to get to the first hole. While we were in line, the front desk told everyone that they’d run out of adult-sized clubs, and gave us comically small children’s putters. They promised that they’d bring us adult clubs as soon as some were turned in at the end of the course. We eventually got one after we’d started playing the first hole, and wound up sharing it on the rest of the course.

This is a big family activity. Things quickly backed up as large multi-generational groups took their time playing the hole — as at any mini-golf course, you have to be patient when grandma and grandpa are playing with the kids — and there was no way to easily play through, even though we could see holes ahead of us were completely empty. The solution may be to try to get in a round at lunch or first thing in the morning (the course is open 10 a.m. to 5 p.m. daily, with the last admission sold at 4 p.m.).

On Thursday, July 26, and Thursday, August 23, the course will be open until 9 p.m., which should make it a great date-night/pre-happy hour destination.

On Daedalus’ Journey, which is modeled after a medieval labyrinth, the ball travels through multiple switchbacks before entering the main green. (Fritz Hahn/The Post)