Here are four art venues in the downtown Honolulu area that are free and open to the public! These are all within a 20 - 30 minute walk of each other and the Aloha Tower Marketplace if you'd like to stretch your legs and enjoy some artwork for a few hours, or just check something out during a lunch break.

Hawaii State Art Museum
In the historic No. 1 Capitol District building, this is a venue for the Hawaii State Foundation on Culture and the Arts, a state art agency that supports and promotes the arts in Hawaii through various means, including the collection and maintenance of artworks in public buildings. While you can see several works from the collection while out and about (the Public Art Archive is a good guide), most of the collection is on display in buildings that you might not be visiting. The Hawaii State Art Museum makes it possible for visitors to see part of the collection in one place, near the State Legislature and 'Iolani Palace. The galleries on the second floor can be walked through at a leisurely pace within an hour, and are comfortably air-conditioned. The Sculpture Garden on the first floor is a calm, quiet spot that office workers and students enjoy lounging around in during lunch. Partly because the collection is intended for public buildings in Hawaii, all of the work on view is connected to Hawaii and tends to be very viewer-friendly (you can see some examples online in their collection catalog). Docents are available if you have any questions (inquire at the front desk), and there is a small gift shop and cafe on the first floor as well. The location is just a block or two away from various eateries including Cafe Julia, 'Umeke Market and Aloha Salads.
Location: 250 South Hotel St., Second Floor, (corner of South Hotel St. and Richards St.)
Parking: metered street parking on Richards St., or the parking garage in Ali'i Place (1099 Alakea St., $1.50/hour for the first 2 hours and then $3/hour).
TheBUS: several bus lines stop in front of or near the building. Check TheBus.org or call (808) 848-5555 for route and timetable information.
Hours: Tuesday - Saturday 10 AM - 4 PM. Special events on First Fridays and Second Saturdays, and a monthly Art Lunch lecture (last Tuesday of each month, 12 noon - 1 PM, bring your own lunch). This is a state agency, and closes for state holidays including Kuhio Day, Kamehameha Day, and Statehood Day.
Accessibility: There is a ramp on the Richards St. side of the building. Entering the building requires navigating sharp turns in a narrow hallway that opens into another hallway (turn left to get to the elevators and information desk on the first floor). There are two elevators. The restrooms on the first floor include ADA accessible stalls; the second floor courtyard restrooms are single rooms with grab bars.

Honolulu Hale
Similar to the Hawaii State Foundation on Culture and the Arts, the City Commission on Culture and the Arts (Honolulu Mayors Office of Culture and the Arts) focuses on public art from, of, and about Hawaii. Monthly exhibits in partnership with local community organization showcase a diverse range of Hawaii art and artists. You can also see their collection in the Art in City Buildings Program online catalog. Mission Houses Museum is nearby, and the Mission Social Hall and Cafe recently opened there.
Location: 530 South King St.
Parking: some metered street parking in the area
TheBUS: several bus lines stop near the building. Check TheBus.org or call (808) 848-5555 for route and timetable information.
Hours: Monday - Friday 8 AM - 4:30 PM. As this is a Honolulu City & County building, this venue closes for state holidays, including Kuhio Day, Kamehameha Day, and Statehood Day.
Accessibility: call the Mayor's Office on Culture and the Arts at (808) 768-6622 or email moca-info@honolulu.gov for information.

Honolulu Museum of Art at First Hawaiian Center
A partnership between the Honolulu Museum of Art and First Hawaiian Bank, this gallery features contemporary Hawaii artists and Hawaii-based works of art. This is a great spot to see emerging local artists! In the heart of downtown Honolulu, it is easy walking distance from several cafes and restaurants, including my favorite coffeeshop - the downtown location of Brue Bar (119 Merchant St.).
Location: 999 Bishop St.
Parking: the building parking lot entrance is on Merchant Street, $5/30 minutes. While there is street parking in the area, don't count on finding any during bank hours!
TheBUS: several bus lines stop in front of or near the building. Check TheBus.org or call (808) 848-5555 for route and timetable information.
Hours: Monday - Friday, 8 AM - 4 PM. Closed weekends and bank holidays.
Accessibility: call First Hawaiian Bank (808) 525-6340 for details

ARTS at Marks Garage
In the Chinatown Arts District, the ARTS at Marks Garage is a community art center and part of the Hawaii Academy of Performing Arts (HAPA). Exhibits change frequently, and the small venue makes it easy to fit in a quick trip to see what's in the gallery. ARTS at Marks Garage is heavily involved with First Friday, and HAPA partners put on various shows and events, some of which are free, including film viewings, talks, slam poetry, improv comedy, and a board game night (HAPA online calendar). The gallery includes a Visitor Information Center with free street maps, and an ADA accessible bathroom (down a dimly lit hallway in the back). This is a great neighborhood for lunch, dinner, and snacks! Madre Chocolate is across the street, Wing Ice Cream and Shave Ice and Summer Frappe (smoothies and sandwiches) are a short walk away. Several restaurants throughout Chinatown include Southeast Asian, American diner style, and an Irish-style pub that serves pizza (JJ Dolan's). In the other direction, Fort Street Mall is full of cafes and restaurants that cater to Hawaii Pacific University students and downtown office workers (personal favorites of mine include Doner Shack, Fort Street Cafe, and Le Crepe Cafe).
Location: 1149 Nuuanu Ave. (corner of Nuuanu Ave. and Pauahi St.)
Parking: the building includes a pay parking lot (Marks Garage - note that access to and from the lot involves a lot of stairs) and another pay lot is behind the building (Beretania-Nuuanu Parking). There is metered street parking around the building.
TheBUS: several bus lines stop near the building. Check TheBus.org or call (808) 848-5555 for route and timetable information.
Hours: Gallery hours are Tuesday - Saturday 8 AM - 5 PM, with events happening at various hours.
Accessibility: The current entrance and exit doors need to be pushed/pulled open manually and there is a bit of a slope into the gallery from the front entrance. The building has been doing some renovations and some sections may be temporarily closed off.