The street separates the districts of Kallio and Alppiharju, however the part west to the railway underpass belongs to Taka-Töölö.
[1] Between the avenue part and the railway underpass there are only buildings on the southern side of the street, except for the Helsinki Sports House.
To the west of the railway the street runs along the shore of the Töölönlahti bay and the only buildings on it are the Finnish National Opera and Ballet and restaurant Töölönranta.
Rental apartments were small and business premises with display windows were built on the ground floor.
Between the northeastern shore of Töölönlahti and the railway Eläintarhantie made a 90-degree turn so that its ending part was a direct continuation of Helsinginkatu.
To the west of the square, also to the south of the street, is the Aadolfinrinne square with its two curved stairways, which lead up to Aadolfinkatu onto the Torkkelinmäki neighbourhood in front of the former main building of the University of Tampere (formerly located in Helsinki), Franzénia, which currently hosts a kindergarten.
The intersection between Fleminginkatu and Helsinginkatu has traffic lights, and its northwestern edge opens into a small concrete-paved square.
There is active tram traffic on the short part between Kaarlenkatu and Läntinen Brahenkatu, because it is trafficked by the lines 1, 3 and 8.
Immediately to the west of the Kirstinkatu intersection on both sides of Helsinginkatu are the Josafat cliffs and the Tauno Palo park opposite each other.
To the west of the Sturenkatu intersection, south of Helsinginkatu is located the Helsinki Deaconess Institute building complex.
Helsinginkatu goes underneath the railway track to the west of the Deaconess Institute and continues along the northern and northwestern shore of Töölönlahti.
The Eläintarha park, whose Helsinki Winter Garden is visible to Helsinginkatu, is located to the north of the street.
There are traffic lights on Helsinginkatu at the following intersections: Hämeentie, Fleminginkatu, Kaarlenkatu, Sturenkatu, Vauhtitie, Mäntymäentie, Oopperankuja and Mannerheimintie.
The southern sidewalk of Helsinginkatu connects to the avenue going around Töölönlahti immediately to the west of the railway track.