You must find five curatorial lire in the Streets course in Tony Hawk's Pro Skater 1 + 2. These are scattered throughout the level. You must acquire them all at once to complete the challenge. It can be difficult to keep track of them, so we've documented them all and the best way to reach them.
All lifejacket locations on the streets
You can find the first life jacket pretty quickly at the start of the level. If you look to the left, you can see it floating down the side of a wall. All you have to do is go back up the hill, but don't go over it. Once you're at the edge, go up the wall and jump to grab it. You don't need to fill up your special bar to reach it.
The next one is at the bottom of the hill, in the courtyard on your left. You should see it floating near the back, to the side of the building. It is in a location similar to the first, just above a ramp. You can do the same here and go up the ramp, jump and grab it.
The third life jacket is a bit trickier to acquire. You can find it in front of the large building with the "San Francisco" sign above it, floating in front of it. It's in the middle of a pair of ramps. There are two ways to acquire it. The first is to increase your special meter, and with that activated, try to jump between the two ramps and grab the life jacket in the middle of the jump. The second method, and probably the most difficult method, is to slide the wall to either side of the life jacket, and when you're close enough, take a jump to gain enough momentum to get it.
The fourth life jacket is in the middle of the square, in the center. You won't have to do anything too creative to achieve it. All you have to do is perform a few jumps to get to the top, and the collection is yours.
The final life jacket is cleverly hidden. You can find it on the corner of the map, right next to the bank. The fastest way to reach is to reach the bottom of the hill when you start the course. Instead of going left to get the second life jacket, go right, then take another right at the end of the street. The life jacket will float behind the laundry panel.