Halloween has come a long way from its roots as the ancient Celtic holiday of Samhain, marking the end of summer and the beginning of a new year. The early Christians co-opted the holiday, turning it into “All Hallow’s Eve,” or the “Eve of All Hallow’s Day,” giving us the name Halloween.

Putting on costumes was part of the original Celtic festivities, but I doubt if they dressed up as Harry Potter or Sponge Bob Squarepants.

Whether your children prefer traditional scary Halloween wear such as Frankenstein or The Mummy, or their favorite TV cartoon character, there are plenty of opportunities to take your costumed tykes out for Halloween fun this weekend and on Halloween, which is Monday.

For those adults who still enjoy the opportunity to let their inner child out for the evening, there are activities for them as well.

Several cities are hosting downtown trick or treating, which is a safe way for the kids to get their fill of free candy without parents having to worry about whether the treats contain any tricks, and several area churches are hosting activities to celebrate the harvest, rather than the “pagan” holiday.

Here’s a roundup of events happening in Kitsap County:

+ Mystery on Callow: Metropolis, the Gallery and SpecialTea Pots hosts “Mystery on Callow,” 7-9 p.m. Oct. 28 at the gallery. This is an interactive mystery theater for adults in which participants try to guess the answer to the mystery of the Egyptian statue. Cost is $25 person, and includes drinks, finger foods, live music and prizes for best vintage costume and best solution to the mystery.

Advance tickets are available at Metropolis, 318 Callow Ave., Bremerton, SpecialTea Pots, 320 Callow Ave., 360-479-1661 or online at www.specialteapots.com

+ Downtown Bremerton: Downtown merchants will hand out candy, host free hay rides, a haunted tunnel and a monster mash, 5-8 p.m. on Halloween. The USS Turner Joy on the Bremerton Boardwalk becomes a Halloween Haunted Ship, open to all for $5 each, 5-9 p.m. Oct. 28-31.

+ All City Halloween Party: Bremerton revelers can head to the Sheridan Park Community Center for the All City Halloween Party, 5:30-7:30 p.m. The event is free and includes a costume contest, pumpkin carving contest and carnival games.

+ Monster Bash: The Admiral Theatre hosts a “Monster Bash” Halloween party, 3 p.m. Oct. 29 at the theater, 515 Pacific Ave., Bremerton. The party is geared for children ages 6 and younger, and features a costume parade, prizes for best costumes, dancing to classic Halloween songs, goodies and more. Tickets are $6, with one adult free per paying child. Purchase tickets at the theater box office or by calling (360) 373-6743.

+ Ride on the Ghost Train: South Kitsap Parks and Recreation District is offering rides on a special Ghost Train, 6-9 p.m. Oct. 29, at South Kitsap Park, corner of Jackson and Lund in Port Orchard. Ride is $2.

+ Halloween concert: Bible Baptist Church, 6703 Bethel Rd. SE, Port Orchard, hosts a Halloween gospel concert with The Down East Boys from Riedsville, NC, 6:30-8 p.m. Oct. 31, free.

+ Mall Halloween Carnival: Kitsap Mall in Silverdale hosts its annual Halloween Carnival Oct. 31 beginning at 6 p.m. with trick-or-treating in the mall, carnival games and more. A good place to get out of the weather if it rains. Event is free.

+ Mystery author: Children’s fantasy/mystery author Michael Buckley is the guest of honor at the Barnes & Noble Halloween party, 4 p.m. Oct. 31 at the Silverdale store, 3108 NW Randall Way.

Buckley will read scary bits from his new book, “The Sisters Grimm: The Fairy Tale Detectives.” The bookstore will have cookies, puzzles and seasonal souvenirs for little trick-or-treaters until about 8 p.m., or until supplies run out.

+ Frightening farm fare: Pheasant Fields Farm, 13274 Clear Creek Rd. NW, Silverdale offers Wild Woods haunted maze and spooky woods, 7-9 p.m. Oct. 28 and 29, $7.50 adults, $5 children younger than 15 and Tales of the Deep Dark Woods, for adults, younger than 17 with parent, 7 p.m. Oct. 30, $7. Information at (360) 697-6224 or www.pheasantfields.com.

+ Haunted barn: Check out the Halloween Haunted Barn at Kitsap County Fairgrounds, 6-10 p.m. Oct. 28 and 29 with the theme, “Fairy Tales Gone Wrong.” $5 per person, ages 5 and older, $1 off with canned food donation.

+ Downtown Poulsbo: Front Street will be closed to car traffic as merchants in downtown Poulsbo welcome trick-or-treaters on Halloween, 4-6 p.m.

+ Port Gamble party: Dauntless Bookstore, 4790 NE SR 104, Port Gamble, is hosting two Halloween parties, 10 a.m.-noon and 2-4 p.m. Admission $5 per child or one canned food item. Port Gamble businesses will also be offering treats for trick-or-treaters. Map and list of events at Dauntless Bookstore.

+ Bainbridge festivities: Bainbridge downtown merchants host trick-or-treaters from 4-6 p.m. on Halloween, with music by Mike Sharp’s Band and free hot cider at the gazebo on Winslow Green and ghostly tunes from the Eagle Harbor Church bell tower from 4-5 p.m. Look for the orange pumpkin posters in the windows of participating merchants. Non-spooky Haunted House at Kids Discovery Museum, 305 Madison Ave., 4-6 p.m. Donations accepted on behalf of the Teen Center. wu