Going on a Knightwatch Medieval sleepover was particularly thrilling for us since my family has a long personal history with the Cathedral: It's where I went to grammar school and now my daughter attends summer camp there. Plus it's one of our favorite neighborhood destinations with its gorgeous grounds, playgrounds and art-filled interior.

The sleepover starts around dusk and consists of four main activities: a dance lesson, an art workshop, a scavenger hunt/interactive show and a brief celebration before everyone goes to bed (not that you get much sleep). When we arrived, we were immediately organized into three groups. After my daughter designed a coat of arms for us, we went to the basement to learn some Medieval moves. It was a bit of a slow beginning to the evening, honestly, especially since the modern looking gym broke the mood. The art workshop was a much bigger hit, as the kids (and parents—you don't get to sit on the sidelines) made clay gargoyles, did brass rubbings and chipped away at a big block of limestone.

The main event is the scavenger hunt/interactive show, which takes place throughout the Cathedral. The King explains that his daughter the Princess needs our assistance to break a magic spell that prevents her from speaking. If she can't talk, she can't say "I do," at her upcoming wedding. The Court Jester leads everyone all over the building looking for clues that will help the damsel in distress. In between, scenes play out that give you the back story of all the characters and, of course, it becomes clear that everything is not as it seems.

My seven-year-old daughter absolutely loved this part of the evening. She was totally into the mystery of it all and enjoyed talking to the actors. However, I did spy a few older tweens rolling their eyes. Yes, it's a bit cheesy, but if you've got fantasy-obsessed kids who love things like the Renaissance Faire, they'll totally eat it up. Even the shy kids got into it thanks to the Jester, who was great at getting everyone excited about the task at hand.

The night ends with a brief party (that's when those Medieval moves come in handy) and a bedtime story. By midnight, everyone's in bed (or, more accurately, on cot) but like most sleepovers, there's not a lot of slumber. Families are encouraged to bring flashlights so they can explore parts of the dark Cathedral, and the older kids stayed up whispering and running around.

The Cathedral sleepover is a bit different from the ones at museums or zoos, which have traditional educational activities. It's an immersive experience from the moment you set foot inside with interesting tidbits about Medieval pastimes and the building's architecture along the way. You really need to play along to get the most out of it. Dressing up is encouraged! The night we went, only a few people came in costume (including me and my kid—someone actually thought I worked there so I guess I looked convincing). It's also probably more fun to go in a group. Once the lights went out my kid was bummed she didn't have anyone to pal around with.

Things to Know Before You Go

The Knightwatch Medieval sleepover is aimed at children ages 6 to 12 but I think 7 to 9 is the sweet spot. Older kids act too cool while younger ones may have trouble following directions. Plus the Cathedral can be a bit scary in the dark (on the night we attended, one family with little kids actually ended up leaving). Children under 6 are not admitted!

One adult must attend for every three children.

Up to 75 people can sleep over, but since you're organized into three different groups, no activity ever feels that crowded.

Eat a big meal before you arrive. Only light snacks and breakfast are provided and no outside food is allowed.

Bring warm clothes and a sleeping bag! I totally didn't heed the warning to do this. I just brought a blanket because I figured it couldn't be that cold. Well guess what? It totally is. While my daughter slept snug as a bug in her sleeping bag, I spent the night with my teeth chattering on my cold cot in the cavernous nave. At one point I started whimpering, I was that uncomfortable.

Sign the necessary release forms before you arrive. It really speeds things up at check-in.

Check the list of items to bring with you. Once you're there you can't sneak out to Duane Reade for a toothbrush.

They kick you out early: 8am to be exact, which means you're woken up around 6:45am. Make sure you don't have a lot on the agenda the day after.

This sleepover, like most of the others, is quite pricey so you really want to know that you're going to have a good time. If your kids are introverted or not into role playing, this probably isn't for them. But if you've been to the Medieval Festival in Fort Tryon Park and loved it, you're going to have a blast. And remember, the money goes to a great institution. The Cathedral hosts some of our favorite annual events, like the Blessing of the Animals.

Knightwatch Medieval sleepovers take place at the Cathedral Church of St. John the Divine, 1047 Amsterdam Avenue at 112th Street. Cost is $135 with discounts available for groups of 15 or more. Visit the website for the schedule of upcoming dates. For further information, call 212-316-5819 or email nightwatch@stjohndivine.org..

Find out about other offbeat NYC sleepovers at zoos and museums.