Doors Open Denver is one of the best deals going. More than 60 buildings, old and new, put out the welcome mat for the public over the weekend, and it’s all free. In addition, there are scores of expert-guided tours offered at no cost.

But it can be a lot of work to sort out the list of sites. Do you want to see historic structures or modern rehabs? Do you want to stick to a single neighborhood or cover some geography?

This year’s theme is “City Beautiful Then & Now,” harking back to the early 20th-century movement to create elegant, expansive architecture in urban areas.

The list includes older, ornate structures around Civic Center, like the just-refurbished McNichols Building, plus scattered landmarks, like the Zen Center of Denver, at 3101 W. 31st Ave., as good an example of classical revivalism as you’ll see in the West.

But there are also recent structures built to serve a civic purpose with the same spirit.

You can get into the first floor of the Clyfford Still Museum at 13th and Bannock streets, or see the new Denver Crime Lab, at West 14th Avenue and Cherokee Street, one of the guided tours. “These are the buildings that will be the landmarks of the future,” said Annie Levinsky, executive director of Historic Denver, a partner in the event.

Check out the list on the website, denverarchitecture.org, and match it to your taste for exploring. Here’s advice if you are willing to dig deeper into the possibilities.

1. Look for deals. Like getting a free tour of the Molly Brown House, which usually charges $8 a person. The 1889 Queen Anne mansion will be open both Saturday and Sunday as part of the guided tour offerings.

2. Look for opportunities. Like seeing the fascinating Dikeou Collection of art in the Colorado Building on an actual weekend. The contemporary museum, at 1615 California St., is one of Denver’s best-kept cultural secrets due to its limited, weekday hours.

3. Look for specials. Like the one offered by the Denver Animal Shelter, which is cutting adoption prices in half to capitalize on the crowds. The shelter, at 1241 W. Bayaud Ave., is so deluxe you might feel guilty bringing a pet home to your own ordinary house.

4. Look for line-cutting opportunities. Like the V.I.P. pass. Many of Doors Open Denver’s organized tours fill quickly, and you have to register for them in person. That means showing up at the McNichols Building headquarters at 8:30 a.m. to claim your place, even if your tour doesn’t start for hours.

But you can also buy a V.I.P. pass, which will allow you to score a spot in advance. They cost $100, though the money supports the event’s operating expenses. Think of it as your charitable contribution to the Denver Architectural Foundation, the hard-working nonprofit that puts it all together.

5. Look for what’s new. Like Hogle-Allison Motors at 1278 Lincoln St. The 1924 structure, designed by Fisher & Fisher Architects, is home to the Colorado Ballet’s studios, but they’re moving out soon so the building’s fate is up in the air.

New sites are always Doors Open Denver’s big attractions. This year’s fresh offerings include the Kittredge Building, at 511 16th St., one of the first elevator buildings in Colorado; First Baptist Church at 1373 Grant St., with its rooster spire; and the Mathews-Gott-helf Mansion, at 2601 Champa St., the 1880 home built for mining magnate James F Mathews.

You can get info at the McNichols Building, or you can simply walk into most of the sites on the list.

Ray Mark Rinaldi: 303-954-1540, rrinaldi@denverpost.com or twitter.com/rayrinaldi

DOORS OPEN DENVER. The annual open house for architectural sites takes place at various locations around the city from 10 a.m.-4 p.m. Saturday and Sunday. Register for guided tours beginning at 8:30 a.m. each day at event headquarters in the McNichols Building, near Colfax Avenue and Bannock Street in Civic Center. Free. doorsopendenver.org.