Plant flower beds or other low-height herbaceous plants that won't block visibility (grasses, ivy, etc.) - and keep them well-maintained.
Improve the lighting. Think about lighting your building's façade, entry, or roofline, or adding light posts around the property perimeter. But adding "twinkle" or "bee" lights to trees or shrubbery on your property is one of the easiest -- and least expensive -- improvements you can make.
Put up seasonal and holiday decorations - not just at the end of the year.
Put one or more benches outside -- even if you have to chain them to something or take them inside at night.
Events & Activities
Host a monthly picnic or potluck in your building's public space -- invite tenants to bring and share food.
Set up a book fair or book swap: invite tenants to bring books they no longer want to trade with others.
Invite tenants to create and care for a "community garden" space.
Host a performance by a choir or musical group from a local church, school, university, etc.
Invite the mobile post office, blood bank, bookmobile, or other community-service vehicles to set up on your plaza.
Publicize other downtown events at your building -- and attend them!
Find out what the DOT is doing to slow down traffic and/or encourage transit use -- and how you can help.
Is there a bus or transit stop on or near your property? Work with the transit authority to make it into a real place with seating, flowers, a bulletin board, shelter, and lighting.
Promote bike trails, transit lines, van services, and other commuting alternatives to your tenants.
Plant something in a barren tree pit -- or contact your city's street tree program and offer to care for the trees it plants near your building.
Community & Civic Life
Know the staff at your neighboring buildings. Talk to them about partnering on activities, programming, or amenities like an information kiosk or vendor.
Install a community bulletin board in or near your building.
Go to a meeting at the city council or downtown association or BID.
Learn the local zoning laws.
Write a letter or article about downtown for your local paper.
Markets & Local Economies
Publicize your local farmers' market to your tenants -- or participate in getting one established.
Develop a skills bank where people in your building or nearby can pay or trade for services and skills. Publicize it on the community bulletin board (see #16).
Get together with staff at neighboring buildings (see #15) to organize a street festival or block party to promote your tenants and local businesses.