There is a slight similarity to the NASA rocket launch pad at Cape Canaveral in Florida. There is a tall tower to the north of the structure for that contains the stairs. At the top there is a gantry. If you are feeling fit you can climb up the many steps by the side of the yellow arch to gain access to the viewing platform. It is a long way up and in the heat and humidity of Colombo it is not a to be taken lightly. Go slowly and drink water. If you do not like heights forget even attempting the ascent. If the open stairs don’t make you feel queasy then the gantry will finish you off. Next to the temple is the Colombo Maritime Museum which is housed in what used to be the old Dutch Prison. That is also worth a visit.
Getting to the Sambodhi Chaithya temple and Dagoba is not that easy. It is best to go all the way down to the roundabout outside the neo-classical Presidents Secretariat building (the old Ceylon colonial Parliament building) on Lotus Road by the sea front and head north up the Chaithya Road as far as you can go. Hire a Tuktuk and take a slow walk back enjoying the sights after you have been to the Sambodhi Dagoba and temple.