  Synoptic magnetograms and relevant proxy data were analyzed to study the
evolution of the Sun's polar magnetic fields. Time-latitude analysis of
large-scale magnetic fields demonstrates cyclic changes in their zonal
structure and the polar-field buildup. The time-latitude distributions of the
emergent and remnant magnetic flux enable us to examine individual features of
recent cycles. The poleward transport of predominantly following polarities
contributed much of the polar flux and led to polar-field reversals. Multiple
reversals of dominant polarities at the Sun's poles were identified in Cycles
20 and 21. Three-fold reversals were caused by remnant flux surges of following
and leading polarities. Time-latitude analysis of solar magnetic fields in
Cycles 20--24 revealed zones which are characterized by a predominance of
negative (non-Joy's) tilts and appearance of active regions which violate
Hale's polarity law. The decay of non-Joy's and anti-Hale's active regions
result in remnant flux surges which disturb the usual order in magnetic flux
transport and sometimes lead to multiple reversals of polar fields. The
analysis of local and large-scale magnetic fields in their causal relation
improved our understanding of the Sun's polar field weakening.
