Mayor Bloomberg, and Human Resources Administration Commissioner Verna Eggleston of the Department of Human Resources, far left, joined by Manhattan Borough President C. Virginia Fields, far right, on Aug. 12 opened the city’s first H.I.V./AIDS Services Administration “model office,” located in the Amsterdam Center at 400 Eighth Ave. at 30th St. HASA is the largest and most comprehensive city-run H.I.V./AIDS service program in the country, providing a wide range of financial benefits, case management, housing and support services. The Amsterdam Center, which also houses HASA’s Serviceline, is the gateway to HASA services for many clients from throughout New York City.