On a budget, skip Berlin TV Tower (Fernsehturm) — the spend outweighs the payoff.
~€25 (timed) / ~€30 (fast track)
On a clear day the panorama is unbeatable — you orient the whole flat city at a glance, and the revolving restaurant is a kitschy retro thrill. The catch: tickets are pricey, queues are long without a timed slot, and on a grey day it's a dear ride up to murk.